Oh man. I've just *understood* what Planck's Constant is.
Planck's Constant is the amount of energy you can fit in a single wiggle. *Any* kind of wiggle. If it's a wave, then its one-wiggle energy is Planck's Constant. Doesn't matter how fast the wiggle is moving or what kind of particle it is(???) or what its environment is like. The smallest amount of energy that can make a single wiggle must be >= Planck's Constant.
This also is why the Planck Length is often called the smallest length that can exist: the Heisenburg Uncertainty Principle is related to Planck's constant, 'cause a "particle" is really just a wiggle and it's hard to pin down the exact position of a wiggle.
So if Planck's Constant is the energy of a single wiggle in the smallest wave you can make, the Planck Length is the size of that wiggle.
So Quantum Physics 101: Everything is a wave. (Even if it's a particle, it's a wave too.)
Waves are discrete. "It's a wave" means a *standing* wave, like a guitar string being plucked. It only exists when it vibrates at its natural frequency, or some harmonic frequency of it. (The posts at the ends of the guitar string are the energy potential well it's in, kinda... regardless.) So it's either one wiggle per interval, two wiggles per interval, three, or some other integer number of wiggles.