I think two of the biggest things for me were:

Keeping a cascading daily log of tasks, thoughts, sketches. Every evening I assess what I completed and start the log for the next day with tasks I didn't finish from the previous day, and new things I want to tackle. It's helped me be productive and is a positive reinforcement loop for being productive.

Second is exercising in the morning, and stretching. It makes a world of difference in terms of health, flexibility, and compensates for stationary computer work for the rest of the day. Not to mention, it wakes me up and boost my mood.