Sluggish? Slow? Constantly choosing to feel a large resistance to movement? Well, the motivation you seek is really a synonym for momentum, and the best part about that definition is how it implies previous movement, acceleration, velocity, the works. Momentum exists after movement has occurred and allows for movement to be increased serving as a platform, so if motivation is equal, then action must derive motivation. Then, it is by doing stuff that we continue to want to do stuff and hence continue the doing of stuff. So, in these moments of lethargy, pick a baby step and just do stuff. Brushing your teeth for ten seconds beats zero, and as you do all these small things you’ll garner more momentum and soon the baby step is a bigger step, relatively of course.
Meditate.