Some valuable tips. Thanks for sharing.

I have a question from community. Like many I have a routine of creating a to-do list. Often times I end my day with guilt that I didn't do much despite of finishing tasks. It also happens that if I am doing an important task, after X mins I feel to give up and not fully engaged. While I feel this i start feeling bad and try to fill the slot with another task which often makes me unsatisfied and not happy. I feel I did not utilize my time. I don't know what should I do.