muscels build up to what u want them to do... if u want to build up fast muscles then do fast exercises... if u want slow but powerful then do weight training... etc. as far as hardening goes... ur body is great at adapting. y do u want them hard? so u can take hits?? if u want to take hit s then take hits and the'll grow stronger and harder and bruise less... making ur body adpat to what u want it to do is by far the eisiest and cheapest way...
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run before you fight fight before you injure injure before you maim maim before you kill