Edmond Lau at The Effective Engineer has recently written an interesting way to stay motivated and remain positive by reframing current life goals as stepping stones rather than ends in themselves. This relieves the pressure of achieving something significant, instead focusing on growing significantly.
The perception that a dissertation is a masterpiece plagues grad students (a trap I fell into), and can easily lead to burn out and disappointment. But graduate school is nothing if not a path where mistakes are supposed to be made. It is precisely the sort of stepping stone the Lau and the cited research by Dr. Heidi Grant Halvorson refer to.