If you find Keen's vibration is distracting to others in quiet situations, such a classroom or library, 

OR 

if you find that Keen's vibration is not strong enough then this page is for you.

Keen has two settings you may adjust.  Open your app, go to the band icon, tap right or left, and you will see the Keen Overview screen.   You will see two Vibration Settings, Intensity and Duration, that you may adjust between High, Medium, and Low to suit your needs. As well as short, medium and long.  As you adjust the settings, Keen will vibrate to provide an example of the setting. You can also adjust the number of vibrations you receive in 45 seconds.