Simply put it is Mass in Motion. A Huge Ocean Liner (lots of Mass) moving very slowly is hard to stop and will crush the dock even at slow rates of speed. A small bullet (low Mass) at very high rates of speed will knock you over, even if you're wearing a Kevlar vest.
Most of us are small enterprises. But with consistent action we can create momentum. Momentum creates results significantly larger than either the mass of the speed alone would create. Working together the effect of impact is multiplied.