This is more of a personal than a philosophical question, but I thought it would be interesting to see what everyone thinks are the main things that make life worthwhile.
I'd say for me it is fun, realised by the process:
the unpredictible/unknown -> discovery -> experience.
This is basically 'learning' so we can apply a formula using the known constant that 'half the fun is in the learning' = 50% fun. If half of what we experience after learning is fun, then that gives 50% + 25% = 75% fun. Some people derive the other missing 25% fun from watching other people having their bad 'half of what they experience'. These people are sadists and are quite manic. I maintain my 25% not-fun so that I remember to enjoy my 75% fun.
The second half of this reply is pure comedy intent (although the sums are in the ball park)!
Oxygen. I love oxygen, life would be downright unlivable without oxygen. I loves me some oxygen.
Seriously, In my life I feel that the meaning of life and the thing that makes life livable is appreciation. Appreciation of the world around me, the food I eat, the people that love me, and even my precious oxygen.
Back when I was digging holes for a living, out in the hot sun. I would stop and wipe my face and breathe in deep and look around and fall into great appreciation of that white sky and the buzzing of the insects and that hot heavy air. How much I appreciated being there and getting to witness all of it. Eating my food slowly and sucking the flavor out of the food smashed between my tongue and palate, it's a wonderful thing. Kissing someone that loves me and smelling their face and hair. Appreciation of all things.
Everything is dying. Entropy swallows all things, and will continue to do so until there's nothing left. The only thing one can aim for in a situation where eventual annihilation is the only possible result is to achieve the maximum possible before the end.