Directly lifted this from Reddit’s AMA with Col Chris Hadfield so I can read it everytime I am having a bad day. It is so great to see someone so clearly in love with what they do and share that love with the world. 

[–]ColChrisHadfield[S] 733 points 22 hours ago

Decide in your heart of hearts what really excites and challenges you, and start moving your life in that direction. Every decision you make, from what you eat to what you do with your time tonight, turns you into who you are tomorrow, and the day after that. Look at who you want to be, and start sculpting yourself into that person. You may not get exactly where you thought you’d be, but you will be doing things that suit you in a profession you believe in. Don’t let life randomly kick you into the adult you don’t want to become.

Per Ardua Ad Astra (through adversity to the stars)