I'll keep my luck then and wish you that perseverance you are looking for! Sounds like the writing should be no problem, so I'll touch on the activity. Find something you enjoy doing. Of course as a fitness professional I advocate for a balance among all aspects of exercise--strength, flexibility, endurance, etc. However you'll be more likely to stick to something if you pick a mode of exercise you enjoy. Once you get in a routine of daily movement, then you can start working on adding in different things to balance it out if you like.

Also remember to be kind to yourself and listen to your body. If you haven't been active in a while make sure to take anything slow and work your way up. I'm happy to cheer you on if you need a little boost! :)