About physics?

Try to start with applied physics.  Something that ties in with what you already know.  what kind of athlete?   Long Jumper?  Dynamics may help you understand how your speed and take off angle effect your distance.  Ice skater?  How friction melts the water under your skate blade so you glide over the ice. 
If you live in a dark place where you can see the sky at night, maybe the physics of the stars and planets.
I guess the best thing is to take something you are interested and follow it down to its fundamental core and that will be physics.  Then use the study of physics to make that more interesting.
I wish you well.

An introductory course in physics it will cover many topics at that level.

So why again do you want to cross?.....

I want to become a professional athlete. I’m afraid wanting something is a start but it won’t be enough ;-)

Have a native speaker of English rephrase your question.  It SEEMS to say that you have no basic knowledge of physics, but that may not be what you are trying to say.

If you are in college, that is truly scary.