I am usually either depressed or anxious and I feel different. I want to feel good and I heard of this principle online, but am very confused by it.

There is this principle in behavioral psychology that if you want to think and feel happy, positive, and enthusiastic then you must act happy, positive, and enthusiastic. The principle even states to act this way even when you don’t “feel like it” or when it feels unnaturally acting that way. I’ve heard from people who promote the idea, that eventually the emotions and thoughts will correspond with the emotion.

I want to ask, is it even possible to act a certain way and then feel the emotion associated with that act. If there’s is any person who tried this method and had success with it, please tell me how you were before you tried it, what did you do to fulfill the “Act As If” Principle, and how did you feel after. I, honestly, am a little skeptical of the whole principle and want to hear a success story because if it’s true then that would be great and I try it as soon as possible.

My second question is if you act in the way that you would like to feel and think like. Since this “new you” that you’re acting like is different from how you act now. Wouldn’t that be similar to “acting like a poser” because you are not being yourself. I always hear that the “poser” starts to get depressed because his actions are essentially fake and not aligned with who he really is.
Or is there a difference between “Acting As If” and acting like someone you are not. Any answer would do.

I really do hope that people feel comfortable sharing their stories and opinions because I really want to know the truth behind this idea, so that I can try myself and get out of this depressed, anxious lifestyle.