79 hours a week
There are 24 hours in a day. Over 7 days, that makes 168 hours.
Subtract the 40 hours you need to spend earning your paycheck, and the 49 you should be spending asleep.
Take 89 hours out of 168--that leaves you with 79 hours a week for The Rest of Your Life: creative passions, friendships, fun, love, activism, self-care. That's a lot of things to fit into 79 hours.
How are you spending them?
I'm not asking what specifically you're doing with your time--your priorities and the demands on your attention are probably different than mine. I'm asking if you're spending the time you have in ways that make sense given the things you tell everybody you care about. We all say we have values, we all have these ideas of who we are, and about the rightness of what we do--but what, daily, are you spending your time *doing*? Are the things you do every day moving you toward not just your visions of justice, but your visions of your own future? Or are you spending your time at a job that sucks so you can come home to Twitter and Tumblr and feel righteous about your choice of retweets?
79 hours is all you get, and the only person responsible for whether you spend those hours in a way that's fulfilling and meaningful to the pursuit of your goals--big or small--is you.
A minor edit--it's been pointed out that I didn't include 'commute time' in these calculations--for me, that alone takes up at least 21 hours of the 79 'free' hours a week.
I lumped those 21 hours in with the 79, though, because I've found that the commute is one of the best times to organize my work on my passion projects: review prior and upcoming commitments, draft e-mails, read items I've queued up. On top of my paid work, of course, I still do something like 12-16 hours of work a week doing hosting, sound engineering & booking for Voices of the 99%, and I have other mercifully smaller organizing commitments as well. Using my transit time to do some of this work means that the otherwise 'wasted' 15 hours on the train goes towards work on a project that I claim matters to me.
I have to use my commute time making progress on my passion projects, or I'd be lapsing on my promises regularly. I don't expect that's true of everyone, though, so it's fair to say that maybe rather than 79 hours, your time is even scarcer than mine: you only get 58 hours. Your hours are indeed fewer and more precious under this new math, but the question remains the same: are you being smart with your time, or not?