I'm not a fan of standing desks for myself - I inevitably find myself leaning or unfocused. Dependent on your situation, but the things that work for me:

- see a personal trainer once a week (over Zoom). Forces me to show up, don't have to be disciplined.

- Set a daily step goal. Start where you are, and try to add 500 a day per week.

I think walking is the best exercise because everyone knows how to do it, low risk of injury, and you won't burn yourself out.