well id fight for what any shonen character fights for, self-expression and to prove my mettle as well as achieve peace in myself after the good fight is over, then restart the entire cycle over again
I'd probably not fight unless forced, and more or less my style would consist of, "Give up now, or get pounded into the ground." Killing would be probably not one of my objectives. Being a protector or self sacrifice would be my drive.
Because I would want to do something interesting. I wouldn't fight out of boredom persay, rather I'd fight because it's something I semi-frequently do anyway and it's interesting to be engaged in any type of combat. Life and limb being at stake makes the stakes interesting enough to warrant it.
I'd be the typical main character guy that has the basic girl harem. Childhood friend, tsundere, a shy one or a smarter one, a blonde chick, a buxom babe, a loli, etc. And I'd go for the loli. ALWAYS. I'll always go for the loli chick.