Just exercising will not make you stronger. If it did, marathon runners would have the largest and strongest muscles. If you want to make your muscles stronger, you have to exercise them against resistance strong enough to damage the muscle fibers and when they heal, they will be stronger.  A review of 22 studies on how to grow larger and stronger muscles found that the best way for untrained people to grow muscles is to use lighter weights with more repetitions, even though most trained athletes gained more strength by using heavier weights with fewer repetitions [1]. Lifting lighter weights with more repetitions reduces your chances of injuring yourself….