you literally can't get more than 40 hours of work out of people anyway.
For most of our existence as a species, 18-24 hours of work per week has been the world-wide average time spent satisfying our basic needs. All the rest was leisure, endeavours in curiosity and socializing. This observation still verifies with the few primitive tribes still around. It also verifies in our records of ancestral agricultural tribes. That's the intensity of work our bodies have attuned to over hundreds of thousands of years of recent evolution.
From my professional experience too it verifies, and I'm curious about what other people may want to report about that. People around me may log long or short hours over the days but once you substract the pauses, all the staring at the screen in a blank mind right after lunch or at the end of the work day, all the heated discussions about this hot topic or that, all the trying to figure out or motivate yourself about what you should be doing next, and concentrate on the actual, value-adding focus and thinking and doing, that's hardly more than 3 to 5 hours a week-day, typically 1-3 hours around 10 in the morning and 2-3 hours around 3 P.M. Even middle management types who try to commit, who show up first and leave last everyday, spend most of their time socializing rather than actually organising things up (basically they're downrate, modernized tribes' chiefs).
If you've got a flexible enough mind, it's a lot more efficient for you (and healthier and easier and saner and...) to wake up without an alarm clock, and not rush to the office, help yourself with organising your tasks with basic methodology, then get stuff done in those 4-5 hours. And outside of those hours relax, talk with your colleagues, allow yourself to enjoy your lunch, etc. There's litterally no point trying to force it beyond that.
Also, you'll benefit immensely from cutting the crap out of your life at home too. Stop inflicting incessant news updates, FB status updates, tweets and 24/7 information TV on yourself, your brain is NOT built for that kind of abuse. Stop thinking in terms of pain/gain balance: an hour of treadmilling is not compensating a handful of cupcakes, not in any way you can measure utility for yourself, ever ; and similarly inflicting huge stress and deadlines and job abuse on yourself so you can then indulge in a more wasteful home and car and lifestyle is NOT balanced either.
That one most precious but limited resource that you have in a basically fixed amount for life: your time... stop throwing it away so liberally. You just need to spend half as much as your income (give or take a quarter of your income, there's quite a margin) and then you can get retired in your 30s (or 40s if you're already late in the game), even on a $40-50 000/year job.