Welcome Kittylover!
Start slow. That is what I had to do - I went from perfect weight and amazing cardovascular health and strength to total non-activity (due to moving out of state, divorce, lack of caring) and gained over 100 pounds.
At first walk slow, no matter the distance and work your way up to a faster pace (my "fast" and other people's "fast" are two different things, whatevah, I'm not exercising for them). Start with small distances and work your way up. Don't even begin lifting weights - just use the weight of your arms and legs for now, when that gets easier *then* make it harder by using weights, cans, your cat....
The good news - out of shape people increase their health and strength leaps and bounds faster at first than someone who has been active and is already fit. You'll feel better faster and you'll be able to see and feel it faster. Once you're fit, the benefits are still there, but it takes a LOT more work to increase your health and strength once you're there.
You can do this! I did and I'm still working back to where I was, but there's nothing better than being able to hot-foot it a mile or so, get a little sweaty and feel fantastic when I'm done. I'm thankful every day that I had the "umph" to get started again because that is the hardest part - getting started!
I know it's hard, really I do. I hope this helped somewhat and feel free to jump in on any thread that strikes you. I hang out with the 5 Pound Challenge folks which is an addition to the 21 Day Challenge thread. I was a WW leader for 3 years and worked with Jazzercise for about the same amount of time - I have just enough knowledge from nutrition in college to be dangerous... I hope this helped you some??
Welcome again!!!
Terri