You accompanied your best friend to the gym because he asked you to help him, and you wanted to keep him company, so why not?

you were sitting on a bench when he suddently called you. "Oye, come here" he simply says, a slightly softer tone that for you wasnt anything new. "sit on my back" he says while lying down, propping himself up with his forearms, his hands clenched into fists.

"You said you were willing to help me, so come on" He tells you impatiently. "I need a weight on my back"