Enthusiasm is the power that transfers the mental blueprint into the physical dimension.
Whenever you are engaged in something and there is an outpouring of energy, you are in enthusiasm.
Enthusiasm is intensified enjoyment of what you are doing.
Enthusiasm is when the universe creates through you. You are involved in a creative act. You are bringing something new into this world. When that energy comes in, you feel an intense aliveness that flows into what you do. That is enthusiasm.
Enthusiasm cannot be a continuous state. It comes in waves.
Sustained enthusiasm brings into existence a wave of creative energy, and all you have to do is 'ride the wave'.