Build the tool YOU want to use!

Recently, I was reading the latest blog post by Paul Graham: http://www.paulgraham.com/greatwork.html

And this one is my favorite part:

If you're making something for people, make sure it's something they actually want. The best way to do this is to make something you yourself want. Write the story you want to read; build the tool you want to use. Since your friends probably have similar interests, this will also get you your initial audience.

He continues with that if you go down that route and make what an imaginary, more sophisticated audience wants, you're lost!

What is your favorite part? What part kept your attention?