The last month or so my arms have been getting really tired while playing. I can only make it through maybe 2 fairly demanding songs before I have to take a break for a few minutes. Is there some exercise like push ups or lat pulls that could help to make my arms less tired. Do I even need to build more muscle or just exercise more? I'm a bit overweight and should be exercising overall just to help increase my stamina, but anything specific for arms?