Honestly it can be anything...
Fun
Time
Family
Happiness
Fulfilment
Love
Success
It is really up to you.
Oh, you want to know the meaning?
Not sure what it is... but you can chose the path you take to eventually finding the meaning to your very existence:)
I know which one I would pick:
Ha, you wanted to know?! Not telling you.
Sorry if I gave you an existential crisis...