What is a good exercise to strengthen my legs?

My guess is that you aren’t walking or exercising enough. The Post Office is looking for letter carriers.

Squats?

Climb up and down stairs.

On several websites it states “jelly Legs” or “rubbery feeling” is attributed to muscle weakness that occurs when the body is flooded with adrenaline.
Another is attributed to build up of “lactic Acid” ( a metabolic waste product gained from working out.
Both suggest Dehydration and to drink more water, stretch the legs muscles for about a min or few.
Takes electrolytes and sometimes Potassium,Magnesium needed.
Also not to workout the legs two days in a row but to give the muscles time to recuperate in between.
Years ago I used to work out the upper body Mondays, Wednesdays and Fridays and the lower body Tuesdays,Thursdays and Saturdays.
Sundays reserved for recuperating and relaxing.
Swimming and light walks helps as well.

Go up and down steep hills a lot.

There are muscles in our legs used for a variety of tasks. In order to properly increase the strength of all muscle groups, you will need a variety of exercises.
There should be a trainer who can help you choose the workout best for you, and to help you set up a schedule. You don’t want to work all your muscle groups the same day.

If they feel rubbery I highly recommend you get your vitamin D checked (blood test) next time you go to the doctor.

To build strength you might try weight training, or stair climbing, but I still say you have to rule out D deficiency first.

You could also test magnesium and iron.

If you have pain in your legs while exercising that can be arteries getting blocked, but since you are t winded I highly doubt that is the problem.

Do you feel anxious several hours after working out. Like when you lie down in bed at night you feel edgy after working out that day? Unexplained anxiety?

Working out does not cause extra anxiety. If anything, it relieves anxiety, at least while I am exercising.

I will ask my doctor about this the next time I see him.

@LostInParadise I agree, unless the muscles are fatiguing fast from lack of vitamin D. I’ve seen this in a lot of people now. The exercise helps with stress and overall outlook on life, I completely agree with that, but then the lack of D possibly raises some other chemical in the body that causes an edgy feeling during the time the muscles recover, it’s not immediate. It’s a very physical feeling, not like anxiety from depression, racing thoughts, or fear.

I’m interested to know if the OP is experiencing it, I’m not making any assumptions.

People say to exercise to feel better, but when your muscles cramp easily, weaken easily, and shake, and then you deal with a free floating anxiety feeling from the exercise (most people don’t connect the two though) and even to the point I couldn’t wear clothing at night with tight arms or couldn’t wear many layers. It doesn’t sound like the OP does a lot of arm exercise, but that might be a bad assumption. Plus, I work out later in the day, so that is probably why I was feeling it at night.

For me the exercise was a mixed bag when this was happening. I had to be careful not to push my muscles, but the cardio was great from a psychological standpoint, that’s the endorphins you’re referring to. People would say do weight training, but they didn’t understand what was happening when I overworked my muscles, and the muscles (all muscles) were overworked with little work.

It doesn’t sound like the OP has an extreme case like I did, but my D goes extremely low without large doses of supplements.

I not only ask in the interest of connecting data, but because if it is happening it might be helpful.

To be clear, I am not telling anyone to take D, I’m telling jellies to get it tested and see where you are at, and then address it with your doctor.