If you want to bluebirds of happiness to nest in your mind, then you have to clean out last year's detritus. Replace regrets and resentments with kindness and patience--toward yourself, of course.
Let those old thoughts come. Tell them "Thank you for coming. I don't need you any more. You can go now." Yes, be kind even toward those negative thoughts that traipse around in your mind.
Notice the quiet incubation of calm.
The bluebirds of happiness will be hatching soon.