Feature Requests

You calculate the heart rate zone according to the formula 220-age which makes sense but could be far too low for active people. I would be nice to be able to set up heart rate zones manually.

Ability to see correlation between two metrics over time

Add the option to choose whether a photo is shown for each metric or an icon

ability to customize the unit system used for certain metrics (for example, choosing Celsius for temperature while everything else remains in Imperial units)