You want to work hard enough to get results.  But not so hard that you get injured and laid up for six weeks – and there goes those results.  How hard you should train depends on three factors: The goal – Are you trying to lose weight or win a powerlifting competition? Your current level of activity – Consider the feasibility and safety of training 5 days a week if you’re currently doing next to nothing. How you feel that day – Probably not worth going for personal bests on d