You cannot feel happiness in the future. The future is not here yet. And all we really have is the present moment. So you must BE happiness itself. You must be the embodiment of happiness. It is not something outside yourself that you must track down and find.
The path to happiness is happiness itself. It is not an achievement. You cannot prepare for it, practice for it, apply discipline, and follow prescribed maps. This is what Kim Nam-joon means when he says, “Happiness isn’t something you have to achieve.”