Everyone thinks that their body fat percentage is lower than it actually is. If you think you only need to lose 10 pounds to get to around 12% body fat and show off those abs, then it’s likely you actually need to lose 20 pounds. It will take you twice as long as you thought to reach your goals.
Learning to play a musical instrument to a decent standard so you can play in front of your friends without being embarrassing will take twice as long as you initially thought.
Getting your first website up and running properly will take you twice as long as you initially thought.
Building a business and getting it profitable will take twice as long and be twice as difficult as you initially thought.
It turns out that the quickest way to make money is by making it slowly.