Most of what we say and do is not essential. If you can eliminate it, you’ll have more time, and more tranquillity. Ask yourself at every moment, 'Is this necessary?'
Marcus Aurelius
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Beïnvloeden van gedrag De nieuwe wetenschap om verandering te leidenJoseph Grenny, Kerry Patterson, David Maxfield, Ron McMillan, Al Switzler
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