There’s a lot of evidence that successful people get that way in part by saying “no” regularly. They’ll stop doing things that aren’t working. They’ll turn down opportunities to take on more so they can focus intently on their work that matters. They care more about doing a few things really well and making an impact than they do about having a long list of involvements.
Stanford professor Jim Collins calls it a “Stop Doing list.”
Author Marcus Buckingham says in his book The One Thing You Need to Know that the key to sustained success and happiness is to “Discover what you don't like doing and stop doing it.”
Seth Godin points out that “just saying yes because you can't bear the short-term pain of saying no is not going to help you do the work.”
Study skills author Cal Newport calls it under-scheduling.
And entrepreneur/author Derek Sivers uses his "HELL YEAH! or no" test to decide what he’ll spend his time doing.
It’s easy to fall into the college admissions trap of believing that one more activity, award or accomplishment is all it will take to make you even more competitive. But you only have so much time and effort to spread around. Spread them too thin and you’ll make small contributions to lots of things. Say no regularly and you’ll make a big impact on things that really matter to you.