We use the word "trust" in many different contexts. A living trust is a legal financial agreement. Trust can be reliance on a person or entity. "Mutual trust is a shared belief that you can depend on each other to achieve a common purpose." (Ten3).
As I listen to Stephen Covey elaborate on his 7 Habits, he points out that trust is based on both character and competence. In other words, to really trust someone, you have to believe that he does what he says he will do AND that he can do what he says he will do.
Think of someone you might hire to perform services for you, say, a landscaper. It's important you work with someone of good character, who isn't going to overcharge you for the materials or make the project bigger than you originally agreed on. It's equally important, however, that she knows what is aesthetically pleasing, knows what types of flowers and shrubs thrive in different climates, and can physically accomplish the tasks involved in creating the desired effect.
Part of competence, then, is knowing yourself well. If I tell you I am going to climb Mt. Everest, and you know I get winded on the treadmill, you may not question my character, but my judgment. You don't trust me to carry out what I say I'm going to do, because you don't believe I'm able to do so.
According to The Stanford Encyclopedia of Philosophy, "Trust is both important and dangerous." It's important because you can't have relationships, personal or business, without it. It's dangerous because if you don't take the time to find out if the object of your trust has the character and competence to perform as expected, you may be in for frustration, disappointment, or worse.
It's not enough to be an honest person. In order to be a person of integrity, you have to know yourself to be able to accomplish what you say you will, and then do it. Then you will be worthy of the trust of others.