There is no such hard bound rule that, you should exercise in the morning. But it’s better if you can do so because after a good amount of sleep at night, body is in good state both physically and mentally to carry out exercises. Since the body is in relaxed state, one can do exercises effectively. Exercising in the morning makes one feel fresh whole day but the feeling is subjective, it all depends on your comfort level and the time which is suitable for you to workout efficiently. The physiological effects of exercises remain same no matter when you do. What matters is consistency. Be regular with your exercises and get benefited.