Hit the swing set. Swing as high as possible, so high you shriek with delight/fear.
Lazy river at the pool. Grab a noodle and sail into the mystic.
Jump right into the middle of the puddle. (Running jumps get extra points)
Snow angel! Do it.
Dance party. (Solo is TOTALLY acceptable. No need to be a dancing queen, just throw on the tunes and move your body.)
Shoes and socks off at the beach. Yep, dig those toes in.
Surprise someone you love with something they love.