There are many places to get templates and make changes. You need to sit down and also address the things you want covered in your contract. With all the examples and templates out there, you do not need to spend the money on a lawyer. I have taken sport law and many business classes. If you are very smart and good at doing your research, you can get it done yourself. Any contract signed can be a binding agreement. Remember, just because you have it in a contract that the client cannot sue you for any reason, they can. The wording may help steer a client away from a lawsuit but it can still happen. Make sure you are covered and you did everything you are supposed to do within your scope.
Here are some examples:
Talk with more trainers that are actually in the field to help with revisions and things you may want to add to your contract.