If you're like most clients (or people, for that matter), you have probably told yourself that you "should" do this, or "shouldn't" do that.
This phenomenon, known as shoulding yourself, can seem like it's helping you - when in reality, it most likely is keeping you even further from your goals. Think about it: if your mom calls and says, "You should have called me earlier," or "You shouldn't say those things to your brother," do you feel good? Do you feel inclined to call her earlier next time, or to stop picking on your brother? More likely, you probably feel guilty, maybe ashamed. Overall, the connotation is negative. Note - "Should" is not more positive than "Should Not"; both arrive at the same feeling.
If you want to build lasting habits and lifestyle change - you need to uplift yourself. One way to do that is first, try to catch yourself shoulding yourself. Then, use that opportunity to create action. "I should have had that salad." OK - let's acknowledge that you didn't eat the salad, but what can you do about it now to feel better? Order a salad for dinner? Take a walk? Prepare some vegetables to serve as a side? You can take back the control of your life by turning your guilt into action.