The idea of working out in the morning as being the ideal time is based on the fact that if you work out on an empty stomach in the morning it will stimulate Growth Hormone to a higher level. Growth Hormone (GH) is one of the main hormones that stimulates lipolysis (fat burning). Also working out in the morning is thought to be ideal particularly for men because levels of testosterone tend to be higher in the morning. All these factors put together make working out in the morning optimal. However, the problem with working out in the morning is that it is quite difficult to do because it doesn't tend to feel really good when you work out on an empty stomach--at first anyways. I do think you can get used to it, but it will take some time.