Most people have about twenty or so years where they muster the energy to deal with the insane intensity of a startup. For a lot of us that is the period from when we are in college to until we are about 40.
A failed startup cost you about two to three years of your life. A successful one is more like eight to ten years.
You only have a few serious shots at this.
Which problem are you deeply, deeply passionate about solving? What kind of company do you really want to build? What is it that you can not not do?