One thing I have come to realize is that it's not hard to get some...any...exercise. Even if you're really heavy, there are all sorts of opportunities to get exercise. You can:
1.) Go walking. Start with 15 minutes a day, then expand it. That's what I did. You don't need a gym membership to go walking. Find a local walking trail. Use your sidewalks (if you have them.) Walk at the mall.
2.) Lift weights. You don't even need weights to do this. Just use something that has weight to it, like a gallon jug of water (approximately 8 pounds.) Or a can of tomatoes. Or whatever.
3.) Use a chair. One exercise my coach at work taught me...is the sit down and stand up exercise. It is amazing how much effort that requires when you're out of shape. The good news is gets easier and you can do more.
So get to it....no excuses! Do something!