So I was thinking the other day that it's very easy to just go hit the heavy bag for a while, to spar with friends or training partners, do pad work, etc. But like most anything else in life, if you really want to see some solid progress you need to have some focus and some sort of goal to go after. So I'm wondering who out there "works on" something while training, and how. When you work on the heavy bag, do you, say, concentrate on moving to your right more, doubling up on the jab, etc. for a week or two? I suppose this is most applicable to guys who don't have a trainer/guys who do a lot of training on their own.