If ever I'm feeling a little glum, the best cure I find is to simply mull over that precise expression of melancholy.
Feeling a little glum
I imagine a gnome-like creature, small, round and fantastical (perhaps even Tolkeinesque), being tickled to death by little roving hands whilst it wears a resolutely grim facial contortion, before it cracks up in hysterical glee. This always causes a fleeting smile and snigger, therefore banishing the former gloom.
The glumness is solved by envisaging Glums. Glums being felt up.