Modern medical tech and practices are keeping us alive healthier and longer. Being disheartened by the fact you still need to eat right, sleep, etc. is like being disheartened that you still need to do regular maintenance on your car and treat it well.
The simple fact is that if you sabotage your body, you'll have more issues cropping up sooner and with greater severity, and if you keep it strong all that medical advancement actually has an opportunity to help you in the cases where your body can't help itself. It doesn't discredit medical advancement, only reminds us that many people's lifestyles can often be more destructive than we realize.
The thing with eating and sleeping right etc is that we know the limits of it: it can keep you alive into your 90's at best, and more realistically into your 80's. Technology on the other hand is completely uncapped. A pill that keeps a degenerate bum alive into the 80's might be really hard to achieve, but the kicker is that once you do, it's just another step or two to keeping him alive until 200.
Isn’t genetics more important? There are families where everyone dies young - look at the guy who popularized jogging. All the men in his family die young. He tried to beat it be exercising, eating healthy, etc. Still died young. Same age as his father.
Others families live into their hundreds without any effort. It would seem the first thing to do is to figure out a way to fix DNA.
In 1986 exercise physiologist Kenneth Cooper published an inventory of the risk factors that might have contributed to Fixx's death.[6] Granted access to his medical records and autopsy, and after interviewing his friends and family, Cooper concluded that Fixx was genetically predisposed—his father died of a heart attack at 43 after a previous one at 35,[7] and Fixx himself had a congenitally enlarged heart—and had an unhealthy life: Fixx was a heavy smoker before beginning running at age 36, had a stressful occupation, had undergone a second divorce, and gained weight up to 214 pounds (97 kg).[8] Medical opinion continues to uphold the link between moderate exercise and longevity.[9]
Not to state the obvious, but old people are really, well, old (and frail).
Your pill would need to do a lot of heavy lifting. I'm no doctor, but your pill would need to deal with mental issues (dementia of all kinds etc) and physical issues, like muscle mass, bone density, flexibility, skin elasticity and lots more.
There are very few, dare I say no, 90 year old that could pass for 70 - what sort of condition would 120 bring? Or 130 etc?
As an expert in one field, used to customers waving their hands telling me "this won't take long for you to do, it's very simple", I feel like your belief in (medical) technology, and what is possible, may be just a touch optimistic.
Presumably some sort of cellular rejuvenation - perhaps a way of gradually replacing senescent cells with healthy cells and/or of activating telomerase without causing cancer - would have beneficial effects across your entire body.
There are already large mammals - bowhead whales - that can live 200 years. Perhaps we can adopt some of their longevity traits without having to become giant ocean creatures.
Quality of life is a thing that a bunch of people miss though. If you're active in your middle ages then you're going to be able to do so much more as an 80 year old. You can also play it risky and be super shitty to your body in your 40s because you can afford to but then the next 40 years will suck. And doctors won't let you just die. They'll keep you alive as long as possible. Staying alive isn't the hard part.
Or taking the car example in another direction, it's like being disheartened that you can't put diesel in your car that takes regular unleaded gasoline
We need the proper fuel, substrates, and cofactors to operate well and not do unnecessary damage
The simple fact is that if you sabotage your body, you'll have more issues cropping up sooner and with greater severity, and if you keep it strong all that medical advancement actually has an opportunity to help you in the cases where your body can't help itself. It doesn't discredit medical advancement, only reminds us that many people's lifestyles can often be more destructive than we realize.