A great way to challenge your brain is to break out of your routines. Doing things differently helps create new brain cells and connections, which may decrease your risk of dementia.
Here's a suggestion: each week, change the way you do something. Drive a different route to work or the store. Hike on a new trail. Cook a new dish or eat at a new restaurant. Rearrange your furniture. Take a shower in the evening instead of the morning. Listen to a new radio station. Wake up early and watch the sunrise. Hang out with a child.