A few weeks ago, I took my first sick day for the year. I was mentally and physically exhausted: disheartened by delays and failures in the laboratory, and constantly bad-tempered from headaches and stress. I started staying up late. I stopped exercising and gave up my hobbies. I ignored my friends, partner and family, irritated by the distractions they presented. I prioritized work to the extent that I became miserable and unproductive, existing on bad coffee and fast food.