I tried but it’s basically drivel. A guy in jail discovers the benefits of regular exercise and writes instructional letters to his son with the enthusiasm of

I tried but it’s basically drivel. A guy in jail discovers the benefits of regular exercise and writes instructional letters to his son with the enthusiasm of someone discovering that adding salt to your food makes it taste better and shouting it from the rooftops as if it wasn’t something everybody knows already. Honestly, what made you recommend this book? What concrete advice in it did you find valuable?