I don't know how they do it, but they really understand my energy level. Now I can change my evening plans based on my energy forecast, because I know it will be accurate.
I also really like this colorful daily timeline; it helps me understand why I'm so tired on certain days. I can even figure out which activities and calls with which people are draining me.
Using this app, I've been able to gently adjust my routine and become less likely to get sick. Apparently, my body is grateful for me taking its state into account.