Recommended exercises/activities prior to surgery?

Hi, friends!

Are there any suggestions for helpful exercises or activities to do before surgery to keep in best-running-possible-post-surgery shape?

Everything I have read so far has indicated that if you were a runner before surgery, then it is more likely that you can be a runner after surgery.  I have not run for the past two years, mostly because it is difficult for me to kick my legs out far enough to find a comfortable stride.  I didn’t even realize this was due to arthritic hips until recently.  (I’m only 40 years old, not much pain.)  MRIs revealed that I will need both hips replaced, but the doc wants to start with just one.  Left THR scheduled for 12/19/17.

ALSO, does anyone have any information about how/why doctors decide to do one hip at a time vs. both at once?  I’m disappointed that I can’t have both replaced at once and just get it over with.

Any suggestions appreciated!

KS