Mindfulness makes people less motivated

This is similar to what I've noticed in my own experience of emotional highs and lows.

Sometimes I feel myself enter into a period of excitement and activity that lasts for a few days. During this time I feel very positive and capable. I get inspired easily and can think quickly. If I let myself get carried away with these moods the feeling increases until I suddently and inevitably reverse and enter a "down" state where I feel the opposite of how I felt in the "up" state.

But if I focus on controlling myself and maintaining an even emotional keel, I find that I can avoid entering the "down" state. The unfortunate part is that "controlling" myself really means not taking advantage of the "up" state and the powers it gives me. It's almost impossible to not get carried away without actively resisting, which is detrimental to my abilities.