> Buy a treadmill

Have one. Plus chin up bar, and there's always bodyweight.

> and jog on it for 20 minutes when you wake up.

That's a routine.

> Whenever you remember to do it.

That's more akin to how my brain functions. But "when I remember" (/ have energy/motivation) is a huuge variable I struggle with.

I understand you mean well but this is a thing I've struggled with for years. It tends to be boom or bust. I can go months with going to the gym regularly and it helps, then things get chaotic and it all falls apart, and it's exceptionally hard to restart, probably because of exactly such an executive deficit such exercise would help with.