Cry it out is not the only sleep training technique. My wife and I have been able to implement a gradual reduction of supports in an effort to successfully sleep train our daughter. We started at four months by making situations that she sleeps easily a little harder: for example she would fall asleep while drinking so we started putting her sleeping bag on after she drank. As most people say, it won't fully click until after six months. Around six months she started to demonstrate that she could fall asleep by herself. By eight months she rejected help sleeping. Holding her and doing things that worked in the past would only make her angry, she would demand being placed in the bed when she wanted to sleep.