Germany is somewhat on the low side in terms of work hours[1]. Their economic gains are from a rather complicated history.
I don't mean to insult Germany - I think their ranking here is actually a good thing. I'm glad they have found a way to keep work from taking over their lives.
> the only country in Europe who are capable of sustaining themselves.
That would be because of the insane class-specific "put option" we call the Euro that was really a disguised bank bailout. German economic policy (be a competitive net-exporter) isn't possible is everyone tries to do it. For a much better explanation why Europe is screwed economically, see Mark Blyth's (prof. econ. at Brown) talks[2] on the subject, which is much better than my rushed explanation.
[1] http://stats.oecd.org/Index.aspx?DataSetCode=ANHRS
[2] https://www.youtube.com/watch?v=B6vV8_uQmxs#t=673 https://www.youtube.com/watch?v=in5M65566iw
Germany made some (good) lucky decisions in the 90s, limiting salary growth and cutting social welfare and pensions which helped with growth in the last decade. This seems to come to an end, Germany will be much less competitive in the next decade compared to other European countries.
UPDATE: I'm sure lots of 'smart' German businessmen or self-employed work long hours just like the rest of the world, not?
But afaik there also seems to be a slightly different work mentality here in germany, where you go to work and actually work, not chatting gossip or read facebook... at least some blog post from non-germans claim this (since I'm obviously biased I can't confirm this).