"Exuberance, Cheng makes clear, is an indispensable part of his scientific life. "It keeps me alive. I like to have fun, I don't like boredom. Exuberance is necessary, you have to have enthusiasm. Any kind of work involves a lot of tedium, menial tasks, boring tasks. Exuberance allows you to see beyond, to see the goal. You need that kind of emotional makeup to push through the work, to pursue really difficult things. Exuberance stops you from getting discouraged, or not starting in the first place. Science is working out ideas. The majority of ideas don't work out, there are a lot of dead ends. You need to have an exuberant makeup to prevent getting discouraged. Exuberance reduces stress levels." Exuberance also allows you to handle rejection, Cheng points out. "For example, if you put in a big proposal to NASA and it gets rejected, you need resiliency to pick yourself up after that. I have a natural tendency toward exuberance, I am naturally inclined to plunge into things. But rough times always come." Work, he emphasizes, is inherently stressful. "Stepping back, relaxing, enjoying, not getting all wound up or spinning your wheels, this keeps you from wearing yourself out."