1. I was getting too attached to TSR. Now I set myself one or two -short- periods daily to log on, and I keep to that. It has worked.
2. As for study, 'divide and conquer' is the only approach (I've tried many) that works for me- as well as being realistic as to the amount of time/work I can do. An example. Let's say I want to revise a set text for a literature exam. It's a big ask to take a 400-page novel and revise. So, I might set a goal to revise one theme in that novel for a specific period of time, or even just look at a single episode in the novel that illustrates the theme, for a smaller period of time. At the end of the set time I take a break and tick off the item of work that I did, which makes me feel better- even if the material doesn't seem like it's going into my head.
3. A small tip that paid off well for me is to disable the sound on my devices that indicates new email. I used to get sidetracked by it.