The best mental state for achieving success:

Long-term optimism, short-term pessimism, and present pleasure.

Because you are long-term optimistic, you won't wallow in self-pity, you won't talk yourself out of things, and you will boldly take action, try things, as only action can lead to results.

Because you are short-term pessimistic, you are cautious, you maintain a sense of awe, and you are always on guard against significant risks.

Because you are currently joyful, you can focus, you can enter a state of flow, and you can mobilize your strongest physical and mental powers to advance things.