Instantaneous personal change

I've reached the point in my life where I need to make some personal changes fast. I've experienced instantaneous change in the past, but I don't understand why.

When I was a kid in junior high school we played
football during P.E. class. I didn't really participate. I just went through the motions and dreaded the experience every day. Then one day I was in the way and the ball hit me and I caught it for an interception. Some kid came by and said "see, that wasn't so hard was it?". Well I instantly became a one of the better players and looked forward to P.E. from that time on.

The second example is dental phobia. I dreaded the dentist and had molars rotten to the gum line but wouldn't go near a dentist. Then one of the molars abscessed and the pain was so extreme that fear or not I had to see a dentist. This resulted in a sloppy extraction where the tooth had to be cut into four pieces and each piece removed separately. From that point on I have had no fear of the dentist at all. I can sit in the waiting room for a root canal and be as calm as if I were in a waiting room having my cars oil changed.

My third example involves my attempt at selling real estate. I was a classic non-salesman trying to make a living selling. I didn't like closing at all. I thought that if I was knowledgeable about real estate people would buy from me which isn't true. You have to aggressively close to sell real estate. One day I made a sale and was on top of the world. But this didn't result in a lasting change. I went back to my old ways and soon had to find another way to make a living.

The point of this post is why did the first two examples result in instantaneous change but the last one did not? Somewhere in these three stories is the secret to personal change which is virtually instantaneous. Wouldn't it be nice to wake up tomorrow and and know that you could vanquish fear and become whatever you wanted to be and do so that very day? I know it's possible because I did it twice but I don't understand why. Any comments or ideas would be greatly appreciated. Thanks.

G Frank