Write it down as people have suggested but also do micro action lists. Eg it’s no good writing “exercise”, it’s like writing “write a novel”: too big a target! Break it down into what you need to do to achieve that, like:
Find old running gear and try on
Order new sports bra
Look up route
Download running playlist
Etc
I achieve much more when I have micro actions I can tackle, because you can pick one tiny thing even when knackered/busy, and the sense of achievement from that spurs you on to do the next thing.
Also, Forest app on my phone so I don’t lose evenings to mindless scrolling, and don’t sit down on the sofa after dinner “just for five minutes” because you WILL be there until bedtime. A schedule, so I know which evening I’m doing what, with several evenings allotted to TV, date night, early night for extra sleep, etc, so it doesn’t all feel like a relentless treadmill.
Takes 21 days to make a habit (possibly, cba to Google it), so pick a quiet month and make the habit of doing things on your micro list and eventually it does stick. You’re just in the habit of not doing stuff, and of doing plans just before bed. It’s just a habit and you can change it