I like when Winston Churchill said:
"Success is not final, failure is not fatal: it is the courage to continue that counts."

As you mentioned, there is a lot to be learned from "failures" so that in an of themselves make them not really failing. I admire this everyday in others as the have the courage to do what they must to pick themselves up when they have fallen and to take care of themselves. In that respect, I do not fear failure as much as I continue to learn how to pick up and move forward from "failures" as well; and believe me there have been some doozies.

Success I have mixed reservations about as there is more fear of this in not knowing how to accept and handle it, especially with the response from those around. It can be unsettling as mentioned above. Plus there are always new things to strive for and the success is not permanent. So trying to take into account any blessings when they occur and then move forward from there as well. No matter the outcome, fears either way, I just keep trying and hoping I have the courage to do so.