What makes someone smart?

Listen, I'm in college right now and I'm getting really worried cause it has gotten a lot harder. My first semester I got a 3.5 now I'm having trouble with stuff worried about if I'm with my friends too much or if I'm working too much or what. I know I'm a diligent worker but a lot is going on in my head, parents, brother, fraternity(SAE), scholarship, and friends....what should my day go like how can I be smart again?