A lot of the issues I found when I was trying to exercise, which I think i've mentioned before, were that my lifestyle simple wasn't up to it, I drove everywhere, was lethargic between locations, and wasn't really that interested in the gym or things like that, as it's not really how I was brought up.
In my past it was all about sport for enjoyment, and exercise was never anything that was done to keep in shape, just par for the course of having fun.
As with anything, it's a job of reconditioning, and something which i'm still working very hard on it taking every opportunity as it comes, and if there's a chance for a quick jog, or a little hop skip and a jump, go for it, it all counts in the end.
Something one of my old friends told me once, while not for the right reasons, has stuck with me. He always claimed he didn't have enough time to exercise, nor to go to the shop, so whenever he did, he'd run, and his saying was that "any task shorter than 10minutes, i'll run to it", so he'd always run to the shop, run for the takeaway, etc. He did this because he was mad, but it's a good way of keeping your body ticking over.
With that in mind, I tried to go to the extremes, and began to run up the stairs to my apartment (2 flights), jog around to the car, power walk to work, carry more shopping bags than usual to save on trips but also train the right muscle groups.
Not many of these things remain, but I have to say I still run up the stairs when I can, and I definitely carry all the shopping in one trip, regardless of what it is - as I hate going up and down the stairs twice for the same thing!
I will warn you though, something that I found very quickly was that because your body isn't used to running up stairs (2 or 3 steps at a time), or your arms aren't used to holding station for so long, small muscle tears were often, and I had an on-going niggle with my groin that kept coming back (treadmill, stairs, etc), but now finally appears to have settled down.
So be careful, but try to push yourself further than the level you'd like to eventually be at.