I highly recommend Jean Moroney's blog. She digs deep into the psychology behind productivity and goal-setting. I found many unique insights in her articles. Thanks to her writing I've come to believe that procrastination often stems from deeper emotional issues or an unacknowledged clash of priorities (for example, when you try to force yourself to do something that you don't, in fact, want to do, the deeper issue is that you haven't resolved the clash between your short-time desires and your long-term goals).
E.g:
https://www.thinkingdirections.com/dont-motivate-yourself-le...
https://www.thinkingdirections.com/three-steps-to-following-...
General list here:
https://www.thinkingdirections.com/category/time-management/