Our bodies are amazing machines that utilize synergistic muscle groups to accomplish a staggering range of motions.  One mistake many people make when they are training is to attempt to strengthen their bodies in a piece meal fashion, that is, one muscle group at a time. 

Well, our bodies don't work like that, so in order to maximize your potential you need to think about training in a way that fully utilizes those synergistic muscle groups.  For example, rather than using a chest press machine, try doing the same 'synergistic motion', using dumb bells and doing a unilateral chest press (one side at a time) on a flat bench with your legs elevated.  This will not only work your chest, triceps, and shoulders, but will make you very cognizant of your care stabilization.  By challenging your balance whilst strength training, you will be focusing on your core strength first.  You will also be promoting better flexibility, and therefore better movement.

So the next time you train, think about training for better movement, rather than individual muscles.