Here's some tips

Manx2004 is totally right about the body weight exercises. Here's my take on things.

3-4 days per week, go for a walk. The pace should be fast enough to get your heart rate up (Diablo iii Gold), but slow enough that you can still hold a conversation. This may be challanging at first, the point being to not be going so fast that you're panting and gasping.

3-4 days per week do push ups, sit ups, and chair squats (just sitting back onto a solid chair or stool, then standing again, no weights). Try for 3 sets of 10 of each of those.

Use knee push ups if you have to, no worries. I'm sure the sit ups may be a bit of a problem, just do the best you can and don't pull on your head/neck. Start with your arms down at your sides, then as you can finish the sets progress to hands on shoulders, then hands on ears, then hands behind head (still not pulling on your neck). As you get better you can progress to burpees (you can google it for a description).

Make sure to have a day or two each week where you're not exercising. Your body needs to recover (Diablo iii Gold), and if you're cutting back your calories it needs time. This is a big change, so take it easy and do small steps that you can stick to, just add to or improve those as time goes on. The little steps add up. That's enough to last you a couple months at least, progressing to slightly faster and longer walks, and better/more reps for your other exercises.

As Manx said, it's mostly diet anyway, but exercise is important too.