I guess there is good evidence that when we have strong emotions, we are not always directly able to be sure of which events and which thoughts, which convictions or memories were used by our minds to launch the strong emotions. So, we look around for the "cause" of the strong feelings. If my gaze happens to land on you while I am sad or elated, I might decide you must be the "reason" for my feelings. Richard Wiseman in 59 Seconds and Alfie Kohn in Punished by Rewards are just two of the psychologists and business theoreticians who study the effect of external rewards, such as a bonus or a gold star, on motivation. Even as long as 15 or 20 years ago, I read in the magazine "Psychology Today" about a scene in the Song of Roland or the story of El Cid where a knight wanted a woman to fall in love with him and therefore killed her flock of pet doves. What the devil sort of wooing is that? I personally wouldn't advise that as a strategy for making a heart beat faster in one's favor. The author said that arousal can be felt but its trigger has to be guessed at, somewhat along the lines of the James-Lange theory of emotion, that we are happy BECAUSE we smile and are sad BECAUSE we frown.
When you meditate or stay aware of what is going on in yourself, you may be able to detect a feeling state inside yourself and actually realize that you can choose whether to let it stay or not. The process is akin to choosing whether to enter a room or not. If you choose not to enter that state, you may find that your subconscious suggests entering the same room just a short time later. If that keeps coming to mind, it can be interesting to try to consciously be in the suggested emotional state but just the state, without harboring any concomitant mental images. If you are really down on yourself for being such a klutz that misplaces a wallet, try feeling purely down on yourself while looking at a flower or a cloud and really studying the sight, without even thinking of the wallet.
You can become far more aware of the workings of your mind. It is sort of pretty in there.
