Pain

The adage, "no pain; no gain," is overrated. You don't have to seek for the pain in order to get that gain. It is always smarter to get the gain without getting the pain. And that applies to almost anything in life. A bit of thinking--creative thinking--is needed though.

Sports scientists knows that very well. Painful muscles are signs of overdoing it. It is always better to train those muscles without having to let lactic acid cause any pain. A brief rest can do the trick. Rest, then do it again.