RE: How long to stay on a routine
you can challenge it enough by increasing the weight. when starting new exercises it can take a few sessions to get to grips with the correct weight to use. if we changed every 8 weeks that wouldnt leave much time to really train hard. next thing you know your changing again. i understand its important to give your body new challenges and it is important to change exercises. but im on week ten of a program im doing, and am making good gains after a dodgy start. i wouldnt change it now to experience the same 'teething' problems. if an exercise isnt going well, give it a chance and change it. if not, i dont think its worth it.