Record your activity level with the number of stars.
You can check your recent activity levels with a colored calendar like table.
Use three stars as the following:

★ : Worked, even if only slightly
★★ : Worked normally
★★★ : Worked hard!

The purpose of this application is to support to form good habits,
so recording detailed content of your activity or looking back the distant past is out of the scope of this application.
Thank you for your understanding.