Mental stimulation

What do you all do for mental stimulation? I would like to “refresh” my toolbox and see what others do. I’ve got a 3 year old long haired girl named Winnie who responds well to the following:
-puzzle toys and games where sniffing is involved
-treat dispensing toys
-short walks with lots of sniffing

I feel like she gets bored pretty easily with her current toys and games, so let me know what works for you all!