Its about building the muscles up around the knee. Take a 5 pound dumbell and tie a two strand electrical wire around the handle. Use a utility knife and gently bring the knife between the 2 strands. You will now have 2 pigtails 5 inches long. Wrap the 2 around the handle and tie a square knot with the 2 pigtails. Now do the left side of the dumbell. There is a loop where you will put your foot into. When you pick up the loop with your hand , it should remain affixed to the handle. Now take a used toilet paper sleeve and cut it length wise. I use 2 sleeves and put the wire inside and then tape close. This is the cushion for the top of your foot. Wear a sneaker or a stiff bedroom slipper. Put your foot in the loop and lift your foot a couple inches off the ground with your knee locked. Lower weight a half inch off the ground and then back up, while sitting in your good office chair. The movement you make is only a couple inches. Bring the weight up and lock your knee then down to floor and back up. When I started I used a 10 pound dumbell and did 25 lifts each leg. I would do 3 sets with long rest times between each. Months later I'm up to 15 pounds and do it 110 times, 2-3 reps per day. Try to do it every day. The muscles got bigger above the knee first then along the outside part of thigh. Now the under side of thigh is getting firmer. The first year was of the 10 pound weight. This year the 15 pound weight. It's the heavier weight that does it. You want to develop your foundation first with the lower weight. It's better. No need to rush it. Nice and easy in 2 years you will feel the difference. Going up and down stairs is easier. Walking is a bit faster and it looks good too. You are making changes for a stronger you. When you stick with it and see the results it builds self confidence. And that is your best reward because you will apply it to other areas of your life.
You can start with as little as a one pound dumbell. I keep a notepad handy and chart the date and year, then my poundage and how many times I do it in a row. When the row is done it's called a rep. I use to get charlie horses which are painful, no more though. I do think the leg lifts helped with that. I can also kneel and get up from the kneeling way easier than before. You want results you will need to put in the time and forget the pills for now. If you do have pain with your knees see the appropriate doctor first before doing these exercises.
Take your time with the exercises. There is no rushing through them.