Take breaks, indulge in /gpose goodness, do lost canal maps, try some furnishing, level a crafter, level a gatherer, try PotD solo, do low level quests as jobs you haven't leveled, join random farms of fights you've done but haven't got a mount, do it just for the fun of it! I don't say all that in a way to minimize the burn out you feel, I just list things that helped me continue to enjoy the game despite being in similar place as you and maybe it could help you too.

Personally, I can't stand the tome grind anymore, nor I have nerves to grind sigmascape and stay at the mercy of rng but I'm thankful we have several alternatives to gain ilvls and tome cap is removed shortly before a patch so catching up isn't too bad. I used to raid and I used to stress having optimal gear but now I'm enjoying the filthy casual life and the game feels less of a chore. I'm yet to get 400 of whatever is the new tome and patch is like 3 weeks in or something.