Cleaning up the kitchen every night.

Used to leave dishes in the sink during college, then do them when it got full. Got a side job as a bartender, where you had to clean up every surface after the last shift, ready for people the next day. Applied it to home. Has stuck ever since.

Fortunately, married a woman who had the same habits. We've never gone to bed with a dirty kitchen, even after a group gathering.

Doing pull ups every other day. Started by doing pull ups every other day

Put everything I need to remember in calendar, reminders or just set a timer. Since I started doing that consistently I never forget anything.

Deal with things immediately if possible or schedule it. That also means cleaning the kitchen after I’m done eating or even while cooking.

Never close the door without me seeing the keys in my hands with my own two eyes. Even if I’m 100% sure they are in my pockets, I will pull them out again. I have locked myself out two times already, won’t let it happen again.

The best habit perhaps is meditating daily and I developed it following Tiny Habits.

GTD is up there too!

Not sure if best, but:

• cleaning the kitchen in the evening. I listen to podcasts or music while doing it, and the mornings are easier as I don't have to confront mountains of dirty dishes.
• reading - I try to dedicate at least one hour a day and read a book. I guess with general decline of the content on the Internet it got much easier to go offline.
• meditation and relaxation techniques - I started doing this as a teenager and thanks to hours I've put in I have no problems falling asleep. Even when I am high on caffeine I can relax my body during the night and wake in the morning not feeling like a zombie.