Indefatigable.
One philosophy that has served me very well in my undertakings is to just keep going.
While some may consider this an inclination towards workaholism, as an adult, I see no time in my day that is not filled with work of some kind. While this will lead to a restructuring of the definition of “work,” I certainly hope you’ll see my point.
It’s very common for Designers and Developers of my age (mid-20’s) to work more than one job, typically in a Day Job + Freelance situation. I’ve also noticed that many such workers, though more appear to be in their 30’s, are also having children.
I happen to be in the enviable situation of mixing both. I have two wonderful children (who conspicuously arrived without instruction manuals); a full time job where I am the primary driver of the Design Department, and have been for two years; an adoring wife whom I cherish like no other, and spend as many moments with as I can; and finally, I’m producing work on the side that I’m unable to put down — the fires of inspiration are burning hot and I’m energized immensely by it.
Oh, and I have to sleep too.
I love my life, and I’m certain that makes a major difference in my attitude. having been on the other side, a life you hate leaves you lethargic, drained and bored (at the least).
Through it all, I can’t stop and say “Sorry kids, I’m not going to be your Dad for a while. I need a vacation.” No, I listen to them, play with them, give them medicine and a snuggle at 3 in the morning and love them the best that I can. A child deserves no less than total adoration.
The same goes for the woman who made my life so wonderful in the first place. She deserves no less than my undivided affection. As Stephen Covey says, “Love is a verb.”
And that truly is the difference between a life drug down by work, and a life uplifted by it: you must love what you do. For then it no longer becomes work, but the genuine outpouring of your heart.

