A good article from Forbes on ways to toughen up your mental state.
Some things to avoid:
Wasting energy on things you can’t control (better to concentrate on the things you can control such as your reactions to difficult situations) and dwelling on the past.
“There is strength in acknowledging the past and especially in acknowledging the things learned from past experiences—but a mentally strong person is able to avoid miring their mental energy in past disappointments or in fantasies of the “glory days” gone by. They invest the majority of their energy in creating an optimal present and future.“
Fearing Taking Calculated Risks
“A mentally strong person is willing to take calculated risks. This is a different thing entirely than jumping headlong into foolish risks. But with mental strength, an individual can weigh the risks and benefits thoroughly, and will fully assess the potential downsides and even the worst-case scenarios before they take action.”
Resenting Other People’s Successes.
“It takes strength of character to feel genuine joy and excitement for other people’s success. Mentally strong people have this ability. They don’t become jealous or resentful when others succeed (although they may take close notes on what the individual did well). They are willing to work hard for their own chances at success, without relying on shortcuts.”
Feeling the World Owes Them Anything
“Particularly in the current economy, executives and employees at every level are gaining the realization that the world does not owe them a salary, a benefits package and a comfortable life, regardless of their preparation and schooling. Mentally strong people enter the world prepared to work and succeed on their merits, at every stage of the game.”