Since i was little, unsure of it all

I'm in my early 20's, don't do drugs, drink very rarely, good head on my shoulders, good paying job (working a lot of hours), cocky of me to say but i'm very attractive, athletic and physically capable of almost anything. Things should honestly be great and the world should basically be mine for the taking... so why do i not want everything before me? Why do i who is so fortunate to have so much going for me have a train of thought that betrays everything i do? I change like the wind, one second i want nice expensive things and the next i don't want anything and i want to give my stuff away. Confidence literally oozes out of me and i only strive to succeed and usually i do, but i never feel that way. I strive for perfection but is being perfect really going to mean anything? I feel life is cruel and you excel and succeed at everything to just die anyways. If death is an inevitability then why prolong and torture your physical and mental state with the arduous task that's living out life? I was wondering really what anyone thought about life and what meaning they find in it and what way of living is worth it. People live out their lives fall in love, have a family grow old and die and call that happiness. I'm jealous of people that from looking at them, you can tell are truly happy. I'm not saying that that's the life i want but more so the feeling of happiness i wish for. I feel both of these answers should coincide with each other and i just would like to here others opinions on it..

I do find things that make me happy but i'm so indecisive as to what i really want, some things that make me happy are selfish desires i fulfill and i do also like to see other people happy. I honestly bear the weight of other people's problems more than i bear my own, prioritizing it usually because i don't like to see others in anguish or grief over their own troubles. I still don't know though because at the same time i say to myself "why do this? Is this really helping in the long run? This has nothing to do with me." My selfish side kicks in and i'm feeling constantly torn about what path is truly right for me because i've only learned that my actions literally effect everybody around me be it their actions there personality or them learning from how i think and act. Whatever route i choose to take i know i'll be fine but i still don't know which one is right because my actions aren't just effecting me but everybody around me. I would just like to hear from someone who had a similar scenario to my own and how they carried on living and what way they chose to live and how it turned put for them and if they have regret.