Think of some super achiever in some particular field, your own even. You will never have that level of talent or achievement, probably. But if that person has achieved what they've achieved through extraordinary mental toughness, then that is something that everyone has, potentially at least, in equal measure. And that is actually more significant than the achievement itself.
That mental toughness is the best thing you can give to yourself. Allow yourself that.
UPDATE: What I mean is this. Mental toughness is the basis of decisions. You can make a decision to act in a certain way, and then those decisions become habitual and thus automatic over time. People can certainly try to take it away from you or encourage you to pursue it, and it does depend--to that extent--on other people. But insofar as it is a result of a decision or series of decisions, it is autonomous.
It is amazing that most people in history, or in the present, have not enjoyed the material conditions that make autonomy possible. At the same time, there is a huge capacity for autonomy in the human character. So it must have always been possible for some people, or else this capacity would not exist in the evolution of the species.
A lot of people can't handle autonomy. I read articles about how mental illness is the hidden cost of being an academic. I have suffered from anxiety and depression myself, but I don't think that's the result of being an academic. It could have happened to me in any profession. Although these ailments are not the fault of a lack of "toughness," a person can improve by taking responsibility for their own treatment. I think the program of meditation, exercise, and socializing is the formula, together with a highly self-conscious work to eliminate decisions that are habitually bad ones and replace them with more positive ones. I could never get with a program that prescribes a belief in one's own powerlessness.