Or, you could raise your rates to the point that you only have a little more work coming at your than the hours you want to work. For example, say you're currently charging $100 an hour and want to work no more than full time equivalent, you'd be bringing in $200k.

Increase your rate to $150 or possibly $200 and your earning potential grows to $300k or $400k.

Obviously, these are made up numbers, and each person needs to figure out the numbers that work for them.