Just finished reading the fitness eBook and I love, love, love it! Wish I could go back and beat 20-year old me over the head with it. If either time travel or beating people with eBooks were possible. I might have avoided the back and hip injuries that now plague me in my late 20s.

I am keen to avoid overtraining, so have a quick question. In terms of "play", I train in Systema and Aikido and my wife and I do various things as the mood takes us: games of tennis, light jogging (never more than a few miles) or sprinting in the park. Now these activities are very varied in effort (especially the martial arts. They're not conditioning-heavy styles so sometimes the sessions are light, but the sensei is ex-military of the most hardcore variety and more often than not decides to beast the class senseless!), so should I be monitoring the intensity of my play sessions to determine when to back off on a sprinting session? Or should I drop the sprinting altogether given my other activities? I don't want to woos out but two LHT, two nights of MA, a game of tennis and a jog and I am up to six days per week! I am not quite attuned to my body yet, so some guidelines would be helpful.

Many thanks!