Goals are one of many ways to get things done.
Maybe, in the case of NaNoWriMo, your goal is to reach 50,000 words in one month. Whether you reach that or not, you’re still going to be writing a lot and it’s definitely a lot more than you would have written if you didn’t have that goal set for yourself.
Setting goals is important. What’s more important is striving to meet them. Have your friends and family urge you towards your goals! You’ll get more done with them!