Good.

I honestly wouldn't over think it much. Start off basic. Push ups. Sits ups. Shadow Box if you want. Jump some rope if you got one. Go for a little run.

All this sort of thing probably won't feel real great at first, but the important thing is to stick with it. First time you jog it can be pretty discouraging. Hurts like hell and you might even puke ur guts out. Not to mention hardly going much distance. Do it for a few weeks tho, and you'll soon realize you've dbl'd, tripled or more your distance and the amount of exercise. From there it just gets better and better.

But I still think you should bite the bullet as soon as possible and get to a gym, because you do know boxing.