40k a year is a lot more than you think. You can live on that pretty easily to be honest. Even afford a nice mortgage.
Here's a sample budget of what it may cost to live comfortably
$1200 mortgage
$200 power
$150 car gas
$600 groceries
$100 phones
$75 gas
$100 car insurance
$75 misc utilities (water, trash, etc...)
That simple little budget, which could be cut tighter in some areas probably, is $2500 a month, which is $30,000. That's probably leaves you a little left after taxes, not totally sure. Then you could build in some clothes, tv, internet, etc.... If you're in an apartment, you could do a little more. The problem comes in with ill advised car payments (you can't afford a brand new Camry on that) and other stupid stuff like financing items you don't truly don't need.
40k/26 pay periods = $1538/80 hours = ~$19.23/hr. This just kind of gives you a reference. Lots of people on here would perk up at the idea of $20/hr for a job.
Are you going to "get ahead" on the above, probably not.
The problem comes in when you're a single parent with no education, making slightly above minimum wage at a dead end job.
$10/hr * 80hrs = 800 * 26 pay periods = $20,800/year. That is rough.