Haha been there, done that, got the T-shirt
Probably a bit late for advice but here goes anyhow
The trick is just to either focus on doing one of those things really well over the space of like 1 month or do a very small amount of each of those things every day
(Like read 10 pages of your book, come up with 1 web-comic idea / do 1 OC drawing a day, do 1 mask draft a day)
Little steps can seem useless at first but it gets easier, and then you can step up your game (to like 20 pages, or 40, or 60 etc) till you eventually forget about procrastinating
Number 1 thing tho is to never give up completely!!
But yh good luck ^^