I never see him train so hard before

My good friend, Roger started to exercise more lately. He started to take more initiative for doing more exercise after his doctor told to him to do so. I never see him train so hard before. He being training to run marathon and now he can run about 2-3 miles non-stop. He wanted to get the best heart rate monitor for his fitness and health training. Anyway, he is now a totally new person for me. I think I won’t be surprise if he plan to hire a personal trainer soon too. Sometime, I wonder whether I should join him and start taking up exercise regularly seriously.