I was especially struck by this example given by the inventor:
It was harder to get rejected than I thought. And that was really amazing for me, that people were actually saying yes. I'd ask for a discount at a store, and they would go, yeah okay I would sell it to you for this, and I was like what? Really?
I had a similar experience:
When the lease for my apartment was up, I asked the manager for a discount. He readily offered me a free half-month if I signed a one-year lease. Which I did. The whole thing took 15 seconds.
That was so empowering. The manager's readiness made me realize that the discount was probably sitting there all this time, waiting for me to ask. I went on to ask for more things, and getting surprised by the yeses I got. Slowly it dawned on me: it is actually hard for people to say no!
Rejection Therapy is a great exercise. Getting comfortable with being rejected gives you the courage to ask for the things you want. And if you don't ask, they cannot say yes. So ask often, embrace the noes, and enjoy the yeses!