Trust me, it is most difficult part to convince yourself to start. And if I understood well, you‘ve already done that. Like others said, make attainable short-term goals. I personaly started with walking. Find a route that you like, find a music that you like, buy earphones (if you don‘t have them yet) and you‘ll be walking miles before you realize it. Take note that there are much faster ways to lose weight, like running, but I find this one especialy good because it takes little effort. It worked for me :)
But key point is to push your limits constantly. Like, this week I‘ll walk 30 minutes every day, next one 35, then 40 etc. If it seems too easy, make it harder. Add extra conditions. That‘s how I did it. Somewhere along the road I found plesure in exercising. Now I do it more to kill boredom.
Good luck. And don‘t give up
Most people fail in life not because they aim too high and miss, but because they aim too low and hit.