JW's attempt to live a saintly life in order to please Jehovah. In the Watchtower society, obeying the organization, righteousness, and living up to 'divine standards' is required for salvation. 
Outward displays of morality, kindness, and perfection is rewarded. Unfortunately, due to human imperfection, these lofty goals are inwardly impossible to fully achieve.
The Watchtower (WT) says, 'Inasmuch as improper use of our hands can result in serious violations of Jehovah’s moral standards, we must be firmly determined to remain morally clean. Therefore, we should heed Paul’s counsel: “Deaden . . . your body members that are upon the earth as respects fornication, uncleanness, sexual appetite, hurtful desire, and covetousness, which is idolatry.” (Col. 3:5) The word “deaden” stresses the strong measures that must be taken to fight against immoral fleshly desires.' Watchtower Magazine, Feb 15, 2009, Article: 'Let Jesus' Sayings Affect Your Attitude', par 12
The Watchtower says that 'God’s servants, young and old alike, must battle to keep free from the contamination of pornography that is displayed on billboards, on the TV screen, in films, and particularly on the Internet.' Watchtower Magazine, June 15, 2009, Article: 'Be “Zealous for Fine Works”!', par 14
The Watchtower says, 'What about premarital sex? That too is against the moral standards set out by Jehovah. ... What about premarital passion-arousing sexual behavior? This practice displeases Jehovah. (Galatians 5:19) The mind must also be kept clean of immoral thoughts. Jesus said: “Everyone that keeps on looking at a woman so as to have a passion for her has already committed adultery with her in his heart.” (Matthew 5:28) Those words apply equally to viewing pornographic images on paper, a screen, or the Internet; to reading accounts of sexual activities; and to listening to suggestive lyrics of songs. Avoiding such material pleases God ... What about flirting? ... How inappropriate it is for single people to send romantic signals to each other just for amusement! What if such flirting is taken more seriously than intended? Think of the emotional pain that it can cause. Sobering too is the fact that flirting can lead to adultery or fornication.' Watchtower Magazine, Nov 15, 2006, Article: 'An Issue That Involves You', Subtitle: 'Avoid Sexual Misconduct
Certainly it is commendable that they teach morality, love, and avoiding things that can potentially hurt other people. The problem is that most people can't live up to the lofty standards of Jehovah. How do JW's feel when they continually fall short of Jehovah's expectations?
The question critics have for the Watchtower is this. Are 'fleshly desires' immoral? Or is this a false assumption? The Bible says that everything God created is 'good'. God is love. Since this is true, why would God give us extremely intense 'fleshly desires' and then condemn us for having them?
A JW could argue that 'immoral thoughts' can lead to immoral conduct. This is very true. No one is arguing with that. Everyone should avoid immoral thoughts. However it would be incorrect to say that sexual thoughts or desires are always immoral.
What if someone has sexual desires for their spouse? Is that immoral? Of course not. Okay then, what if someone has sexual desires and they're not married? Is that immoral? Sexual desires are God given. Why would God give us sexual desires if sexual thoughts and fantasies in themselves are immoral?
Is it appropriate to say that the fleshly desires God gave us are 'immoral'? Think about it. There is a huge difference between 'fleshly desires' and immoral thoughts.
God gave us 'fleshly desires'. Thinking about sex is instinctual. There is no way to turn sexual desires off.
Immoral thoughts are NOT 'fleshly desires'. God gave us sexual desires. He didn't give us immoral thoughts. Immoral thoughts are thoughts about using or harming others to satisfy selfish desires. Immoral thoughts are about self gratification without concern for the well being of others.
The difference might seem trivial. However this slight shift in thinking is important to understand. Fleshly desires are God given, pleasurable, and something to celebrate. Immoral thoughts about using others for selfish gain stems from not loving ourselves and others.
What would cause a people not to love themselves and others? Keep on reading.
When we believe that 'sexual appetite' and 'fleshly desires' seriously violates Jehovah's high standards, what are we to do with that information? Sexual desires are instinctual. Without a 'sexual appetite', all life on this planet would cease to exist. Can we easily turn these desires off? If we can't 'deaden' our physical urges and totally stop thinking about sex, is it healthy to try? And is this what God expects of us? No it is not.
Only an extremely mean, evil God would give us desires so pleasurable and then tell us that thinking about our desires is immoral. What parent would give their child a favorite toy and then forbid them from playing with it? How cruel would that be?
Even though high moral standards and loving people in a non sexual way is something everyone should do, when a JW believes that Jehovah expects them not to entertain any sexual thoughts, they may feel unworthy of God's love and salvation every single time they fall short of His perfect standards.
Having sexual desires and no partner to fulfill those desires with might lead a person to watch pornography, read erotic stories, masturbate, and constantly think about sex. They know this is condemned by the Watchtower and believe that the Watchtower is Jehovah's channel of communication. They fear getting caught, judged, disfellowshipped, and shunned for breaking Jehovah's laws. Worse yet, they know that Jehovah himself is watching. Even if they can fool the organization, they can't fool God.
The inability to turn off these physical desires can cause guilt, shame, unhappiness, depression, loneliness, hopelessness, low self esteem, unworthiness, and so many negative emotions. JW's with normal sexual desires are all alone. If they go to Elders for help, they will be told such desires are immoral unless they are directed towards their spouse. Bible scriptures and Watchtower articles will be quoted. They will be told to stop having sexual desires.
JW's may believe that since they can't measure up to Jehovah's moral standards, they are unworthy of God's love and eternal life.
For example let's assume that a JW is trying hard please Jehovah and believes that thinking about sex is morally wrong. Listen to their self talk. 'Why can't I turn off my sexual desires? I must be the only one. Other people can do it but I can't. I can't stop thinking about sex no matter how hard I try. There must be something wrong with me. I'm defective. I'm not normal. I know Jehovah is angry with me. He can't love me the way I am. I'm not worthy of everlasting life. I'll never make it. What's the point of trying? He hates me.'
We cannot give what we don't have. The more unloved we feel, the more likely we are to hurt people in order to feel just a little bit better about ourselves, - even if the pleasure is temporary.
Immorality is not our sexual urges and sexual thoughts. If that were true, then God would be immoral for making us the way he did. Immorality starts with a belief that we are not worthy and not loved. Immorality starts with a belief that we're defective in some way and there's nothing we can do about it. When we believe our sexual thoughts are immoral and we've failed repeatedly to 'deaden' them, most of us will give up.
Our behavior is merely a manifestation of our internal thoughts. When we feel unworthy, unloved, and 'broken' because we can't turn off our sexual urges, we give up and believe we are immoral by nature. It's a belief there's nothing we can do about it. Immorality is a lack of love for God, ourselves, and other people. 
Ironically then, condemning ourselves for having sexual desires leads to immorality. Accepting our sexual desires with love and kindness means that we have sexual fantasies and desires but we never act them out immorally.
Jesus taught us about morality. He told us to love God and love our neighbors as much as we love ourselves. That's morality.
What would happen if a person changed their story and started talking to themselves in a more loving way? What if they said this, 'God loves me and accepts me just the way I am. I'm sure of that. I have sexual desires and love having them. I am a sensual person. God made me this way and I'm so thankful. There is nothing wrong with my sexual fantasies. I love having them. My mind and body is created in the image of God. I never do anything to hurt people because I never do anything to hurt myself. I love God. He loves me. I love myself. I love others. I am love.'
It's far easier to love others and be concerned for their welfare, when we feel unconditionally loved, happy, accepted, and secure.
Jesus tells us that love is the path to eternal life, not strict rules of conduct. John 3:36; John 17:3; John 6:68; Jude 1:21; Matthew 19:19, Matthew 5:43; Mark 12:31-33; Matthew 22:36-40; Luke 10:25-28
People who feel God's love and follow Jesus do not intentionally harm others. They love their neighbors in the same way that God loves them.
There is no need for any religion to put restrictions on normal sexual desires and attempt to enforce rules that even a saint would have difficulty with. Jesus taught us that love is more important than hypocrisy, self righteousness, and burnt offerings to Jehovah.
Christian religions are 'Christ-like'. They teach love, acceptance, respect, and a belief that eternal life is guaranteed by God when we accept Jesus and follow his example of love.
Love is what Jesus taught and that's what true Christian religions teach. Nothing more. Nothing less.
The Bible says this, 'Anyone who runs ahead and does not continue in the teaching of Christ does not have God; whoever continues in the teaching has both the Father and the Son.' 2 John 1:9
Jesus said, "A new command I give you: Love one another. As I have loved you, so you must love one another. By this all men will know that you are my disciples, if you love one another." John 13:34,35
1. Jesus taught us about love. The Apostle Paul taught us about rules, righteousness, and judgment. Why did Paul add to or deviate from the teachings of Jesus? The Bible gives us the answer. Take a look at Pharisees In The Christian Congregation
2. Divine standards are outlined in this Watchtower publication that outlines Watchtower rules and punishments for disobedience. Shepherd the Flock of God