Taking care of people is hard work. Hard mentally, and hard physically. If I was physically disabled, I'd be unemployed, unless I could leverage what I know into making a living. That would take years, assuming under the circumstances it was even an option.
So as people like John Mosby keep telling folks:
Do your daily PT.
Lose excess weight.
Walk, run, and hike.
With loads. And up hills.
Longer and farther each week.
And not too much.
Ditch the junk food.
Get your rest.
Cut way the hell back on alcohol.
Take your vitamins.
Get a check-up.
Get your teeth fixed.
Take any prescriptions. Squirrel away a rainy day supply.
Get your eye prescriptions up to date, and get spares.
A day doesn't go by that I'm not moving patients, physically. And mine even come helpfully pre-deposited on a gurney most times. (There are the occasional ones who crumple in the lobby.) Think of the biggest person in your family, friends, group of Like-Minded Individuals, or among your co-workers. Whether you want 'em or not, those are your tribes, if crap happens and it's come as you are.
Now imagine moving that person when all the walk has gone out of them. A human body absent functional control is, on average, 100-300 pounds of hamburger, with the rigidity of Jell-O. Ask me how I know this. And if you're not up to the task, you can add a knot on their head or broken bones to their list of problems, when you drop them. You're supposed to be able to help them, and move them safely. Even if that means "assisting them to the floor" slowly and gently, versus doing an Ole' Catch, and watching them hit the deck. And bounce.
You won't be able to do that if you don't do the things on the "do" list above.
If you can't see because you need better glasses, or lost yours and don't have a spare pair, what good are you?
How well will you be able to help if you've got a splitting headache because you're more afraid of the dentist than you are of an abscessed tooth?
The work to learn medical care is hard, and the work of medical care is hard. And when you're dragging ass, beat down, and short on sleep, it's a special bonus of no fun.
Half-day shifts for those of us in the biz are the norm. Imagine how long you'll be on call after a tornado/hurricane/earthquake/etc. Physical stamina gives you an edge nothing else can provide. You can literally leverage health into better mental performance.
Not least of which because healthy people survive better in the first place, all things being equal.
And as studies have shown, if you're tired, you lose IQ points. And basic co-ordination sharpness and fine motor skills. Don't be the shaky stupid clodhopper trying to treat people. Military units, esp. combat units, do everything they can to baby the doc. It's basic common sense. Doc gets a little extra sleep, enough chow, and so on, he might have just that little bit extra reserve to pull your butt to safety when you're broken.
So figure out all the ways you're screwing that up, and get on fixing them.
(And don't kid yourself: you're screwing a lot of them up, probably pretty regularly.)
Make a list of what you should do, and keep doing, and do that.
You're no good to anyone if you can't function.
If you're in rough shape, or infirm, do any and everything in consultation with your doctor and their recommendations. You don't have to pass the Navy Seal Indoc PT test or any such. But you need a basic level of fitness.
You're either fit, or fat. There's no gray area. Nor levels of acceptable fluffiness.
This is your daily assignment for the rest of your life.
There will be a practical exam.
You don't know when that will be.
Weekly/Monthly/Annual quiz (self-graded):
What do you weigh?
What's your percentage of body fat?
What's your resting pulse rate?
What's your resting BP?
What's your Target Heart Rate during exercise, based on your age? (Hint: Look it up.)
How fast can you walk a mile?
How fast can you run a mile?
With a ruck/B.O.B.?
How much can you deadlift?
Can you drag a given load over rough ground?
Can you do it with a notional human-sized 150# load, minimum?
Can you carry a 150# load for any distance at all?
If so, how far?
If not, how much can you carry?
Can you function afterwards for any of the above rather than becoming a casualty yourself?
How much have you improved/worsened since the last time you took this quiz?
What are you prepared to do about that?
Get on it.
Bonus Link: Heads up on how to go about it from Ryan: GMTA.