A Trustee can be considered something like a manager or a CEO of a Trust. With that role, a Trustee has a legal duty to administer the Trust consistently with the terms of the Trust, and the laws applicable to the Trust. Failing to carry out these duties could result in legal trouble for the Trustee.
As a Primary Trustee, you have the responsibility of controlling everything in your Trust. The Primary Trustee will hold the position until they are unable to do so, which usually happens when the Primary Trustee is deceased. At this point, the Successor Trustee will step in to administer the Trust.