Full body stretching and a full warm up before playing makes any musical experience much better. When you are warmed up and loose, your muscles are relaxed and fluid. Try doing this at your next jam/practice... your band will make fun of you but you will be warmed up and ready to rock. Simple take 15 mins to loosen up your body and stretch all the major muscle groups. In turn you wont need to "jam one out" just to warm up.
You will allready be on the ball and they will be a step behind.
Anyways, i could go in to major details but you can check out this great read if you would like.
http://www.amazon.com/Art-Practicing.../dp/0609801775
this book has made me a smarter and better musician.