1) Regular push ups and planks, except when I was injured or on trips. 2) Tracking my diet which helped me lose 10 kgs. 3) Reading tech-related books which only stopped during crunch time at work.
I think seeing results is the main reason I continued these habits. I have tried some other habits like those related to finance or social media but since I could not see any results, they fizzled out.
For the initial push, looking forward to achieving your goals for your habits is crucial. Making sure they align with your own value set is key, so you don't slack off (or pick it up immediately when you do, and that's okay)
And another thing was making the habit small at the start. I didn't go full intermittent fasting or lifting weights since cold start doesn't work for me. It's easier to just improve on the habit as you get the hang of it.