I used Sworkit before it's a really useful app for getting started and you can set it to remind you when to work out. It also has some stretching in it which I recommend you combine with your workout.

Some tips before you start:

1. Plenty water nearby
2. Go easy on yourself in the first week (there's no need to push yourself too hard in the beginning)
3. Give yourself rest days

I like that you're only changing one thing because so many people try to change their entire lifestyle all at once and end up crashing and returning to their comfort zone.

I also love how you're focusing on how fitness makes you feel because there is way too much focus on appearances within the fitness industry and although obviously it does help, it's really not the best thing about being fit!

Best of luck I will be following