Many people believe that bipolar disorder consists of having two completely distinct personality.
Instead, bipolar disorder consists of more or less intense mood swings, that can bring you from ecstatic to severely depressed in a matter of minutes or hours, for no apparent reason.
It’s not something you can train against, it’s the brain chemistry that’s messed up. Meds are an effective treatment.
Bipolar often masquerades as other illnesses, thus is under-diagnosed.