i go to the gym in the mornings and do kickboxing for about 45 minutes, exercise for about 30minutes, weight training for about 30 minutes, and then tan. i have done the same routine for two full weeks and feel fine. but this week, i feel very tired about 3 p.m. and want to sleep which i have and for about 30 minutes and i feel okay. the only thing i changed was the tanning (started yesterday) and the weight training (started today). my question is why after 2 weeks would i start feeling tired in the afternoon now?