One thing that helped me strengthen things was using a slide board.
It simulates ice skating, so you get that sideways movement where you have to stabilize an unstable gliding movement. It also works on that sideways push that is needed in soccer to intercept those darned fast guys.
They can be expensive, but I found one online that worked for me:
http://www.ebay.com/itm/Slide-Board-6ft-x-2ft-NEW-Ultimate-Skating-Trainer-/150511428458?pt=LH_DefaultDomain_0&hash=item230b2e236a#ht_1835wt_1050This is just an example, and you can find them online or at sporting supply stores.
It only takes up about six feet and rolls up into a bag to be put away. You do have to overcome the feeling of goofiness that comes from wearing nylon booties over your sneakers.
This is what gives the sliding motion.
You also have to have enough self confidence to withstand the ridicule of looking goofy to your significant other should he/she see you doing this. To really make a statement, get the pink booties.
I think it's a very good workout for hippies on the later stage of recuperation. It does not slip from the surface it's on and has edges that stop you sliding; you use them to push off in the other direction.
Very good, smooth, challenging and initially (I started at five months) terrifying, since you're sliding using your new hip(s). It's exhilarating after though, since you see that you can control a sliding motion.