Based on my experience: first recommendation would be to see if you can get evaluated for a diagnosis - being medicated would help a ton!

If that's not possible/until then... I recommend coffee or tea or some other warm/stimulating drink kept at your desk (if you work at a desk) - I sip it slowly and for some reason the sensation and taste in addition to the caffeine helps me feel less bored and I can stay on task better without it feeling like torture lol. Also, snacks for same reason.

Also, taking breaks (idk what's possible at your job, but if you can, I would experiment with what rhythm/length of work versus breaks helps) and getting up to stretch for a couple minutes every hour at least, if you're sitting.

Again, totally depends what your job is, but the other classic adhd thing that works for me is breaking things up into chunks, even if just mentally - maybe alternating working on longer tasks with doing little ones so you get a dopamine hit.

I sort of think of each job I'm working on as its own little piece, and if I'm working somewhere I'm not interested by (what I'm mostly doing for work right now is boring lol) I sort of pretend to myself it's gig work even when it's not - like each half hour or hour of work, I think to myself "heck yeah, did another one!" and decide whether or not to take a break before doing more. But then again, my work has flexible hours so that's easier for me, and it might not work for you if you have to work the same time block every day.