Before you respond, ask yourself: Are you and your co-workers truly using your time optimally today? What does that mean? Well: little to no foozball, recreational web browsing, personal phone calls, facebooking, twitter, phone calls, long lunches, late breakfasts, early dinners, personal business, etc.
I find it takes me a lot of self control to limit myself from these things, but when I do, I find myself giving it my all. I also find there's no way to give it my all more than about 6 hours a day, day after day. It's like a professional athlete: recovery is very very important. If you are constantly working without a recovery, you will burn out.
In my 6 hour days, I end up getting about 2 hours of mandatory recovery in there, and even then, it's structured recovery time. I don't hang out with my co-workers or my "boss" - I actually get the hell out of there and talk to sales, marketing, or biz-dev. Otherwise the conversations always degrade into the problem at hand and I lack a fresh perspective.
It's a marathon, not a sprint. But sometimes you have to sprint. If you have a product launch in 5 days and it's pivotal for the company, then you better sprint for at least the next 3 days - pulling longer days. After that, you'll need a proportional recovery. To do otherwise is unsustainable.
That last bit is what has me most concerned about your question - does your manager realize it's a marathon, and not a sprint? He can't just run the engine harder and expect it to perform. Otherwise, good luck in your job search.