Resuming Walking

I haven't exercised in a long, LONG time.  The truth is, I've been dreading it because I have a lot of joint pain that I didn't used to have, so it just hurts.  The shin splints are a killer, too.  But I've got to make myself start doing it again.  I made the decision when trying on a pair of shorts at Target today.  I looked in the mirror and saw sagging skin above my knee caps.  Ummm....I don't think so.  As fat as I am, and have been for most of my life, my legs have always been the most decent thing about me...the thing I was least ashamed of.  I have the calf muscles of a marathon runner and have never had much problem with cellulite or the like on my thighs.  Apparently that has changed, and it's time to do something about it.  I know walking again will tone them up a bit so I'll be starting that tomorrow morning before I shower for the day.  I'll start w/ 30 minutes and work up from there.  The shin splints are going to suck but I'm hoping they'll ease off as I go along.  Wrinkly legs of a 70 year old will be fine...when I'm 70.  Not when I'm 40.