Kills with Bow & Throwing Weapons = 20 XP.Catching Fish = 10-30 XP depending on fish size.
The best way to level up health is by rowing a boat continuously and by doing challenges. More detail about what challenge counts towards what attribute is also in the overview below. We’ll go through all other ways to gain attribute XP below as well. So really, the most straightforward way is to just do challenges, this gets you to level 8 with XP, to level 9 with the outfit set, to level 10 for having done all challenges.