stop holding myself back

I am kinda mediocre at…well everything. Which I guess I am lucky, but since I dont really have that one thing that i am superb at I dont do the other things. I have a nice voice but its not amazing so im not in any choirs or plays, I can draw okay but again not fantastic so I dont take any art classes, I write pretty well but always have a writers block and a weak vocabulary so havnt started that novel iv been fantacizing about for 8 yrs, and I am athletic but not super athletic so I dont push myself to my limit I stop when i get a bit tierd so I dont reach my potential. So basically I want to set goals like write a poem or song- if song- set to music (i play piano mediocre also) each week, draw a picture each week, and put all I have into my workouts and practice, also I should take creative pictures because I have taken a photography class….. Hard to dive into but if i cant pull it off definitley beneficial.