Every muscle in my body aches. That was my cry to a cousin the day after a very strenuous weight training workout with Trainer Jeremy. She became concerned: "Don't do too much. You could hurt yourself." I quickly explained that I have entrusted my training to a wonderful professional and the key to building strength and endurance is challenging oneself to do more every time. The pain is not serious. It is my body's natural response to the work. And it feels good because I know that my …