1 – Something.
2 – Something Else.
3 – Something Again.
You can pick your three reasons, make them up, make them harder and tougher as your work goes by, make them stack on each other, or simply make them so out of this world that you never have to deal with them again.
Or you can ignore them and get to work.
There will always be reasons and there will always be naysayers, but there will only ever be one of you to prove them wrong.