I felt I should pen this one as I believe this is what I'm.
Treat mistakes as lessons; When you do the right thing, you remain modest.
Treat challenges as opportunities; When you face adversity, you remain focused.
Treat failures as successes; When you think you have succeeded, you remain humble.
I never feared failure, in fact never thought I failed. I've always thought I've under achieved. Any achievement is a success. This I think keeps me optimistic about the future.
If we lose our optimism, there are no lessons, there are no opportunities and eventually no success.
I remain convinced that there is no generic scale to measure success, for it is very relative.