At 77 years old, how much exercise can I do?

Sounds about right, for you. But we are all different. Talk to your doctor first. As for me? If I don't sweat it's not sufficient cardio. If it is less than 5 k it 's not enough. Bending, stretching, plank, weights, if it hurts-you are doing/trying too much. Set reasonable goals and be careful.

When I turned 70, my primary asked me about my exercise. I told him I walked, danced tango, swam and did pilate once a week. He looked at me and said, that's not enough. I want you to do strength training twice a week so you will be strong going into your 80's. I am 80, do strength trining with a trainer twice a week, swim once a week often with a trainer, walk, take 4 flights of stairs at least once a day in my apt bldg.

It sounds like you are busy. Ask your doctor if they think it is enough.
We are all different. Keep going.
A little FYI
My dad was in his 90. Leaving the hospital. Doctors told him he needed to exercise.
Can I go get the mail, go for coffee with the boys. All yes they are good for you.
Can I used my rowing machine.
That is good
I was listening to my dad and the doctors
They don’t know my dad. Dad how do you exercise.
I get on my machine and I go until I hear my heart pumping in my ears.
Doctors. Change meds.
My dad was a farmers. You don’t keep them down long

It’s so wonderful to hear the responses!
I’m 72. Lift weights with a trainer twice a week - pilates class twice a week - after a year off I’m back to my walk/running (Jeff Galloway method) twice a week, am at 2 miles. Pelaton once a week. Walk a couple miles twice a week. My goal is more cardio, five days a week. When I stopped running due to ankle problem, my cardio dropped off, and I really notice the difference in my body shape. I started working out when I was about 35.

And setting reasonable goals and be careful, is great advice.

I am 79. Walk my dogs at least 5 times a week. Pilates 2 a week. I was doing weights but now my shoulder is limiting the amount of weight I can lift. I am afraid if I continue, I will injure my shoulder even more. What to do?

I admire your dedication to your body and health, I have heard many times that if you don’t feel pain then you are not doing enough, however consider that you are 79 years old and you should limit yourself, if your shoulders are hurting then it could mean that you’re maybe over exerting, to sustain an injury at our age is not worth it because it takes more time for our bodies to heal and therefore it will set you back for a long time, keep up the good work and always remember moderation is the best way to get there.

Such a great question - whatever age we are. I have a Fitbit Versa 3 on an Australian $120 per year subscription. (Sme may have the Apple Watch with fall detection). I find my simple Fitbit invaluable to track how my body is actually doing. It will work out so much and track it (including sleep, resting heart rate, active heart rate, heart variability rates, intensity zones, steps, distance, calories used etc). It will let me know when I need to do more or pull back and recover.

Please don’t forget “balance” exercises. On top of weights, cardio and flexibility.

I was down the dog park last week and one of the regular ladies had a nasty gash and stitches above her eye. She’d had a fall. Her doctor now has her doing daily balance exercises. I went home and did the heel to toe walking a line the police used to use to test drunkenness. I expected to smash it because it used to be a breeze when I was younger and super active. I was shocked I was so appalling!!!! I had to widen the step before I was able gradually to get down to heel to toe. I do it (and other balance exercises including standing on one leg and gradually increasing time) several times every day now and I’m so very much better.

So important to keep our balance and flexibility as we age.

Sounds great! I have muscle soreness but not any injuries. I agree that you must take it to a pain level to maintan or buid muscle. Also, the rapid blood flow through your brain is good for it.

I’d say as much as you’re comfortable with. If it doesn’t cause you pain, go for it. I know that I can’t do any impact aerobics or lifting weights anymore. What I can do is ride my bicycle or walk for 15-20 minutes. I can stretch. Make extra trips when cleaning house (small arm loads multiple times instead of carrying every thing all at once).
I’m 63 and have some mobility and pain issues. Some days are harder than others and I know my mood has a lot to do with that. I (try to) stay aware of how my body, mind, and spirit feels.
If it helps you, do it. If it doesn’t, don’t.

I play tennis 3xweek. My Dr says do not stop! That’s why you’re 83 and still healthy.