Once hair springs from the scalp, it is considered a dead fibre. Our nails and hair are made of the same stuff: keratin, a protein. Everything we do to our hair is to preserve it. There are no blood vessels, so hair can’t fix itself, or regenerate. It’s dead. The best we can do is low down weathering and protect it from other damage and deterioration. Two important ways to do that are:
Protect your ends--the ends of our hair are always the oldest and most sensitive parts of our hair. All aging things need special care. They've been through some thangs! Tuck them away in protective styles, when you can. Moisturise and oil them frequently. Don't be afraid to part with thinning and split ends. No amount of deep conditioner will fix the latter. You need to
Treat the hair closer to your scalp with care--that hair is fresh, new and strong. But guess what? One day it's gonna be old and weathered, like those ends! Putting in the work when the hair is new (moisturise, don't tug too harshly, do scalp massages, deep condition, etc), it will enter old age in better shape.