1 - Grip Strength (Male: 28kg. Female: 18kg)
2 - Walking speed
3 - How long you can stand on one leg
4 - Whether you can get up from the flour without using your hand
5 - How well you sleep
6 - Whether you still have a purpose

Hey... I cut and pasted that from the Comment section, so I'm innocent!

It also seems to be 6 ways rather than 5, so a Bonus.

The walking speed is important, as is the standing on one foot because that indicates how your brain is performing in keeping you balanced.

Which jives with what neuroscientist Andrew Huberman says about sleep... one of our brain's most taxing jobs is keeping our bodies balanced at all times, and often that's what it's still trying to do when we lay down to sleep.

So there's techniques like Autogenic Relaxation, or as Huberman suggests, the Eye Trick: