Whatever kind of psychological condition a person is in (I'm not referring to mental disorders but, rather, with the day to day mental stuff, or the particular mindset you were raised with).
Examples of mental characteristics (some can be changed or improved, I suppose):
These each take mental energy to maintain, as the neurons send electric impulses down the axons of the neurons. There is less mental energy left for other things. Having a particular mental characteristic is a commitment of mental energy; you choose what to expend your mental energy upon. It consumes you.
To change to a new mode, you have to abandon a current mode, to free up psychological energy.