I work out constantly - everyday / every week, etc I work out consistently - stick to the same or certain routines when working out.

Thanks, Christina.

Constantly means that you do it all the time. Consistently means that you do it at regular intervals all of the time and that people can count on you to do it. "I work out constantly whenever I feel like it" or "I work out consistently every Tuesday, Wednesday, and Thursday afternoon." Consistency is more dependable where constantly just means you do it all the time. I hope this helps!!