In the past I've attempted to be happier by controlling my thoughts only to discover it's as difficult as rowing a boat upstream. In a raging river. Without a paddle. Simply exhausting. That being said, I've found by simply accepting a thought as is, it tends to create a more natural, in-the-flow perspective that ultimately brings peace of mind. In the event a persistent thought causes discomfort say, "I am thinking the thought" followed the the subject or theme of the thought. In doing so, you will find the thought becomes less personal, and the power the thought has over the moment diminishes. Give it a try and let me know what you think (pun intended).