Exercise, or lack thereof

So I don't exercise.  At all.  Yes feel free to judge me, I judge myself.

My problem is that I just have no motivation to exercise.  I have no inner desire to exercise.  On the rare occasion that I do exercise I don't seem to get this elusive rush of adrenalin that everyone talks about.  What is wrong with me??!

Recently I have been under so much pressure at work that it's affecting me physically.  I come home with the worst lower back ever, I'm getting headaches daily, I'm not sleeping well at all (tossing and turning until 2.30am most nights).  I think some exercise would do me a lot of good at the moment.

I'm hoping someone can give me advice on how to ease into exercise, tips for activities that are easy/convenient to do (ie so I can't make excuses).  I can't run (well I physically am able to move my feet but I'm anatomically challenged as a runner and it just isn't pleasant for me) and I'm not very good at ball sports.

Advice anyone?  Please!