Of course, this is neglecting the work involved within the body.  It’d be really depressing if running laps did absolutely nothing for you.

The equation I referred to can be written as such: W=F*d.  The joke revolved around the fact that if the weight or person didn’t end up anywhere, the distance could be considered d=d_final-d_initial=0, which means that W=F*0=0. The only real legitimate thing to learn here is that W=F*d in force and displacement physics.