One of the greatest kindnesses you can do for other adults is to add positive surprises to their lives. Think about it: When you're a kid, surprises are things like "Our teacher let us watch a movie today," "someone brought cupcakes for their birthday," "my parents got me a puppy," etc. But when you become an adult, surprises are things like your car breaking down, conflicts at work, and unexpected bills. No one plans fun surprises for adults, and you can do so much for morale if you do. Ex: One time I found a tiny unlocked door in one of my university's buildings. It was empty, but because I'm a whimsical bitch, I decided to put something fun behind it for the next person curious enough to open it. See below: The Egg Gnome.
The eggs were filled with tiny plastic plants (I tried candy first, but mice got into them, and that's not good for health and safety). Just for the hell of it, I decided to announce the hidden gnome and basket of eggs in the big college group chat, offering hints to which building it was in. People went BONKERS for it. It added fun to people's days as they inspected buildings they went into every day but didn't pay much attention to. They asked me for hints, tried to remember what building had those floor tiles, and proudly announced it in the chat when they had found eggs.
I did several things like that where I just hid things around the university and challenged people to find them, and it did so much for student morale. Some people messaged me to tell me my random antics were their only source of real fun on a daily basis. Adults are just big kids. We're supposed to play long into adulthood, and the games are just supposed to scale in complexity with age, but even simple things like a scavenger or prize hunt can make people so much happier. If you have any kind of morale-keeping duties or have the option to take them on at a school, workplace, etc., I highly recommend planning fun surprises for the people around you. Planned events are a lot of fun, but it's a totally different kind of fun to find out there's a scavenger hunt going on on a random Tuesday.