How important are clubs/extra curricular activities for admission into college?

I am a sopre in high school and have a 4.0 GPA, and have had one for the past year too, but my counselor keeps telling me to join clubs. I play plenty of sports, and the only club I am even mildly interested in is MESA, a math/engineering/science club, but it meets every Saturday at 8 AM, and that is just not my idea of a Saturday morning well spent. My goal is to finish high school with a bigger overall GPA than 4.0, and I know for a fact I can do it. Will I be able to get into the college of my choice purely on grades and athletics or will I ABSOLUTELY need a few clubs? And if I don't NEED clubs, how much will my chances of getting into the college of my choice be affected? I plan on going to Cal Poly or UCI, maybe even Cal State Fullerton.