What does it take to be a college professor in the second decade of the 21st century?
Neil Baldwin in "Conserving Energy" (4.13.17) suggests:
Get a good night's sleep, and eat a hearty breakfast.
I know it is tempting, but don't drink too much coffee, because you will get over hyped before class and risk crashing from that fake caffeine high.
Pace yourself doing whatever you have to do (meetings, errands, paperwork) before class starts.
Remain mindful of your finite energy reserves, and mediate your outflow during class time so you don't expend all your strength too early in the period.
And at the end of your long day on campus, even when you are tired and strung out, the teaching body must be attended to. Make yourself head over to the gym for cardio and weight training, to keep your vital signs in decent working order. Commit to developing the imperative physical stamina required to capture - and hold - your students' attention.