It's for adults- perhaps a paper route is more your speed.
If you're constantly pulling 60 hour weeks (about what you have to pull to bill 40 honestly), you're likely delivering what I am pulling 35-45 hour weeks, billing 25-35, but at a higher cost to your family/health/rest of your life.
That's not adult. That's slavishly burning yourself out in your early years.
Study: http://www.hcgexperts.com/scheduled-overtime-effect-on-const...