Should i still try to do this?

I want to be a rapper but i have a problem with what to write about, i mean i listen to beats that i get from soundclick and whatever the title of the beat is that's what i rap about but people always say, you can rap, you are a rapper but you just gotta come harder. I wanted to be a rapper since i was 6 but it's like i don't know how to go hard with my what i'm doing. why do people say you have to go hard for people to like your music. i put rapping on hold for about a year because it wasn't getting me anywhere and i figure i needed a job, well now i'm 18 and some part of me still wants to rap, i know this is what i want to do because i can't go a day without thinking about rapping. should i continue rapping and just try to find a way to come go harder with my music or should i just quit and find something else to do? How do i go hard with my rapping,i neva understood that.