Check out footage of J Lo and A-Rod during a couple's workout in L.A. the other day -- crushing burpees and medicine ball slams.

Notice anything? Like how Jennifer Lopez is faster, more explosive and more energetic than the WORLD CLASS ATHLETE STANDING NEXT TO HER!!

J LO!!!!!!!!

Of course, A-Rod's built more for power than speed ... but still, watching Jenny from the Block murder this workout is probably the motivation you need to actually get to the gym in 2018.