Don't let that minimum put you off: anything helps, just get started. The hardest, most important part is moving from nothing to something, and doing it consistently. Scaling up from there (if you still think it's necessary, you might not) is easy.
The only exclusive exercise time I have is 14 minutes of
shovelglove on weekdays. So 14 * 5 = 70 minutes a week. It does plenty.
But I also
walk about an hour a day, to and from work, and during my lunch break. I don't consider this exclusively or even primarily exercise: I do it to get where I have to go, to get a little privacy, to see someplace new, to listen to an audiobook, to think. I don't walk super fast or pump my arms or anything, it's just regular walking. But despite the fact that it doesn't feel like exercise, it is probably the best exercise you can do. It's safe, it's pleasurable, it's useful, it's sustainable, and over time, it's very effective.
It doesn't sound like much, and it isn't, but as I mentioned on the no-s home page, this, plus no-s, lost me 40 pounds in a year and kept it off for about 3 more years. If that's insufficiently impressive, consider that the only exercise Jared of Subway fame did to halve himself was walking -- and he walked even less than I do (about 1.5 miles a day vs. 3).
Reinhard