Optimism doesn’t increase your success.
What it does do is increase your field of vision, which allows you to better notice the opportunities that lead to success.
If you have a bad attitude about your job or your relationship or your battle with depression, odds are, you won’t get better because you won’t do the necessary research on the resources that will make you better. You’ll never find the solution that leads to the solution. These are the physical and procedural manifestation of a bad attitude.
On the other hand, consider the show Law & Order.
Before they solve the big case, the detectives always track down the guy who visited the prostitute who sold drugs to the guy who used to share a prison cell with the former roomate of the killer.
Because each of those people is the solution that leads to the solution.
They’re all part of the expanded field of vision.
It’s not about mind over matter, it’s about using your mind to allow more things to matter so you can eventually bump into the best solution.