True. From my experience realizing your unwanted belief and choosing the new one stays just as an idea where we still act in an old way. From my experience, it's because old emotions (energy) are still in the body which is really subconscious mind. So, basically we can do several things:
Acknowledge and feel what we need to feel see it clearly, surrender and ask higher mind to release it
Practice as you said. Here I find hypnosis and meditations + affirmations to be amazing tools. They are also form of experiental yoga where our body is getting used on new feels and energies. The moment body (subconscious) expeience it as real, even it's the result of imagination it becomes real. In other words, we finally act in integrity according to a new chosen belief.
It's not enough to intellectualize it. Realize it. Know it. BE it. Practice it. Immerse yourself into it. Feel into it. ...It really is THAT simple.