What happens to the voice, as one gets older? There are several factors associated with an aging voice and how well it works, or how poorly.
One factor is that, as we age, we lose muscle mass, unless something is done to maintain or build it.
When muscles are not used, they atrophy.
They lose mass and they lose strength.
The good news is that, barring debilitating disease, the muscles can be exercised and strength can be regained and built at almost any age.
Doing the correct exercises, the correct way, can produce results in a matter of days or weeks.
Older people do not have to settle for having older sounding voices.
There are people in their 70s or 80s who sound as if they are much younger.
This is true for singers and for speakers.
If a person has used "non-vocal" muscles for years, the result of atrophy will turn a good vibrato into a slow warble.
As a child I used to hear some older ladies (and men) sound like they had a maniacal trombone in their voices, never on pitch but constantly sliding up to and over pitch.
This can be improved, given knowing and doing the exercises to correct it.
Exercises for the voice should be done a little at a time and gradually increased in frequency and duration.
Too much too soon may lead to fatigue and even swelling of the vocal folds (cords).
Similarly, if you haven't run for a while, you probably would not go out and do 20 one hundred yard sprints in a row on the first day.
An easy and simple way to start is to start humming some of your favorite songs.
Rest between songs, if you feel tired, hoarse, or any pain at all, then stop.
Save it for another day.
It is not supposed to hurt and pain does not equal gain.
Hoarseness means there could be swelling.
Swollen vocal folds are more susceptible to injury and injuries take time to heal, which would only slow your progress.
There are several more exercises, but you want to add them little by little so that you build up instead of tear down.
For speakers, singing is as good for a speaker's voice as it is for a singer.
Reading aloud and even recoding oneself is beneficial in being able to see if progress is being made and if the reality of the sound is getting closer to how the speaker (or singer) is wanting to sound.
It is best to not alter your own voice or mimic the voice of others, when exercising the voice.
That can put undue strain on the voice.
Water can help hydrate a person and gets carried to "the voice" via the blood stream.
Water does not touch the vocal folds, unless you are choking on it.
Being well-hydrated also does not mean to drink so much water as to "poison" oneself with water.
Consult your doctor for this and other physical issues.