I have that problem and it’s still a problem for me but what I’ve found that sort of works is to keep a to do list of all the shit I need to do. Kind of like a bulet journal but less complicated. If someone asks me to do something then instead of immediately jumping on it (unless it’s an emergency) I put it on the list. Then when I am working on something and it stresses me out to the point I am reaching for my phone I move to a different item on the list instead (sometimes). When I finish something or review the list and see a bunch of things crossed off it also gives me a little mood bump. Also keeping my phone in my bag instead of within reach and just listening to podcasts or whatever on my wireless buds helps.

None of this is a perfect solution but it did help a bit. Usually if I can get myself in a groove I can power through several items and make up the time I lost dicking around so having a list ready is handy for that as well.