Hypnotherapy spends considerable time dispelling limiting beliefs. For example:

Therapist: “What brought you here to see me today?”
Client: “I have no confidence. I want to have confidence in my life.”
Therapist: “I hear you want more confidence. Sounds to me like you already have lots of confidence.”
Client: “How do you mean?”
Therapist: “You are very confident you will fail. Isn’t that true?”

Limiting beliefs take many forms; math phobia, fear of public speaking, stage fright, writer’s block. But most are more pedestrian, “I’m just no good at (fill in the blank).” Over time, excuses are created to support the limiting belief; the excuses being further limiting beliefs themselves.
The common denominator of all limiting beliefs is that, even if they are true at the moment, that doesn’t make them true all the time. In other words, limiting beliefs needn’t define one’s self.
What distinguishes the glass-half-empty folks from the glass-half-full folks is their reliance on limiting beliefs. One who sees the glass as half empty accepts limiting beliefs as their truth. Further, they scoff at the glass-half-full folks for ignoring the objectivity of what should be taken to be universal limiting beliefs; as in, “Nobody could be expected to hope for anything better.” Or “Everybody goes thru that (negativity) at one time or another.”

The good news is that limiting beliefs are malleable. For example, that opening exchange on confidence exposes the fallacy underlying a limiting belief. It then becomes a small step to recognizing subsequent limiting beliefs, examining them objectively, and creating positive alternatives.

Over time the positive alternatives transpose into enabling beliefs. The most basic enabling belief is confidence in success; defining success as anything that contributes best to your continued happiness.

In my own life, there was a time when I saw nothing in the glass at all. When I first became aware that I had something in the glass I could only see it as half empty. With much work on myself, changing my mind towards how I perceive my life, I was eventually able to see the glass as half full. After years of learning and experiencing the positive results of my half-full life, I began to expand my boundaries.  Today I place no limits on the possibilities and opportunities in life. Now I have no boundaries. Today I see the life metaphor of what is in the glass as no longer appropriate for me, for I now see it as the wrong size glass. I can choose any size glass I want, so that it is constantly overflowing. Or I can have no glass at all. Happiness is a choice! We are responsible for how we feel. We can choose to feel negatively about something or positively.

Whether you believe you can or cannot, you are right. Can or cannot what? It doesn’t matter; whatever your belief tells you is true you will make your reality.  Belief is a funny thing. It seems very stable and reliable. And that makes it an easy scapegoat when things go wrong. Bad things happen to people who believe they are deserving of such things, and they explain it away by stating that belief in some way, “Of course, that sort of thing always happens to me.”

But let’s say the same bad things happen to people who believe they are capable or deserving of better. Their response is more likely to be, “Wow, this sort of thing never happens to me.”