One of my secrets to cultivating a "whimsical energy" is playing games everywhere I go.
If you pass by hopscotch on the sidewalk, hop every single one. If you see a falling leaf, try to run and catch it. How many people can I get to wave at me today? I bet a dozen. How many trees can I hear creak today? I bet 3.
Also bird watching is a great game. As is "collecting" colors. Basically, like @MOSSYELFIE said, look at everything, find the wonder in it.
I've also started keeping a notebook of sensations. Most of them are delightful–the sight of the water after cresting the hill on a long hot walk through the crowds in the sun; the feeling of the subway seat after carrying 30 pounds of laundry across town because you couldn't drop laundry off on the way to the optometrist because the laundromat was closed; the image of Laundromat George taking his day off, smoking cigs in his backyard. Some of them are awful–the feeling of sand stuck in your sock & constantly rubbing while you can't take it off, how the shadows in the kitchen make you sad because your spouse isn't there to notice them with you, the feeling of lovely weather that is totally in contradiction with your rotten mood. Noticing is a game.