Music can be uplifting and short motivational messages can help too.
An app that combines your favorite music playlist with your favorite motivational messages. After every music piece is played, a message is also played before the next music starts.
Although not a natural way for humans to move in a consistent, efficient way, it might have some interesting uses and health benefits.
Do a study to measure the benefits (or detriments) and changes that occur when subjects exercise daily by running backward.
An interesting way to create a little fantasy.
Use small plants like certain types of cacti as a base for a fantastic depiction of a strange world. Populate the plant’s many parts with minuscule sculptures of people, buildings, etc.
Even if you have a good password for your computer or an online service, it can still be compromised by physical (someone watches you) or technical (key logger) means.
Build a mechanism that allows you to specify two or more passwords for the same account (making sure all of them are good and hard to crack.) Each time you can use any of them except the last one you used. This way if you have been compromised the password thief will still not be able to log in. If you use 3 or more passwords, it will be even safer.
You see a web page that has some interesting elements in it and would like to know how it works. You now have to look separately at the HTML code, the CSS, JavaScript, etc.
Show all relevant code for specific web page object as a pop-up overlay. This way you don’t have to hunt for each code snippet in their separate, distinct source.