Very true. I grew up being terrified of the water. It would happen when I was deep enough for my head to go under, which was caused by my father throwing me into the river when he was "teaching me to swim".I overcame this fear by learning how to scuba dive. Now, I have 7 diving certifications and have literally swam with sharks.
My other fear was of heights. I tackled this obstacle by going sky diving. Not to say I recommend these approaches but....it worked. So, like you've stated, we are absolutely capable of much more than we may think.
That's truly awesome that the OP has tackled his/her fear of rodents head-on and beat it! Definitely something to be proud of.