Kenny, good for you for wanting to do pet therapy with your future Berner!
How to start:
First, when you contact breeders tell them what you plan to do with the dog.
They can better select for temperament by choosing a puppy who is very
people-oriented.
Second, when you get the pup make sure you offer lots of opportunities for
socialization. The more unusual things you can gradually expose the pup to,
the more likely they are to be comfortable in a variety of situations.
Third, sign up for obedience classes. Your dog needs a basic understanding
of obedience commands to pass the therapy test, and you will want your fairly
large grown up dog to be manageable. Don't forget to include some tricks
when you train, like shake hands or something just for fun.
Good luck with that future puppy!
Vicky Hall in Utah