Dear Friend, There is nothing like ideal time for doing exercise in gym. Please do not believe the faslse notion that doing excercise in evening will not give you adequate benefit. You can go to gym any time. Just take care that you should not have eaten a heavy meal befor going to gym, but you must have some light food before going to gym, Aslo before starting exercise and during exercise you must drink water to keep yourself well hydrated.Give time to do cardio excrcises, as they are more important than doing weights  etc. Start slowly, do not try to achive too much quickly, it willl make you prone to injury and fatigue, so take small steps, remeber to warm up and cool down properly before work out. I wish you a very happy and healthy life Dr. Anamay Kamalakar Bidwai Chennai