Are there bad side effects of exercise?
Do you sleep enough and well enough?
You might need a little more when you exercise. When you do hard exercise in the evening it may be difficult to fall a sleep shortly after or you do not sleep as deeply. This may happen unnoticed. Lack of sleep will make you angry. I have experienced the problem during marathon training. Doing intense exercise in the morning or Friday/ Saturday evening (if you don't have to get up early on weekends) helps.
There is also something called ‘overtraining syndrome '. This is when chronic lack of recovery causes performance, health and mental state to suffer. What actually happens in the body is still a matter of discussion and it may take months to recover. But this usually happens onl if somebody is overdoing it over and over again for a long time.