Fitness and weight loss at 66?

Since you have arthritis, obviously a medical condition, is there any chance your doctor would refer you for a course of physical therapy?

Good physical therapists are excellent at assessing one's specific physical limitations and recommending both exercises (or other strategies) for improvements, as well as suggesting things to avoid so as to minimize further trauma. Their knowledge and expertise in these things is much superior to a personal trainer, and consulting with one would be an excellent prelude to engaging a personal trainer.

There also exist exercise programs specifically designed for people who have arthritis. Many are water based (because the water provides support, and some facilities even increase the water temperature during such classes). But there are also things like "Tai Chi for Arthritis". If you are in the US, I've seen classes like this offered by public-school-based adult ed programs, community senior centers, the YMCA, large physical therapy practices or yoga centers, and the like.

If none of that appeals to you, hiring a personal trainer with some rehab experience or education may be next best.

I have some arthritis, some back but mainly hips and knees. I started being active at 46, while obese, shortly after cancer treatment (surgery, 6 months of chemotherapy, 6 weeks of radiation). On top of this, that same year, I was diagnosed as hypothyroid.

I had regular episodes of back pain, which resulted in scary bone scans that involved being injected with a syringe of radioactive material that the technician would bring out in a lead vial to minimize his/her exposure. (They were doing the scans because back pain is a symptom of metastatic cancer.)

I was not a person who did regular formal exercise of any sort. I was an obese, physically depleted, recent widow with a high-stress career and a body that was falling apart. I needed to do something.

I started seeing a massage therapist regularly (on my own dime) and a Doctor of Osteopathy who specialized in manipulation (insurance covered this, plus a couple of rounds of physical therapy for shoulder/neck issues and knee pain from torn meniscus).

I took yoga first, talking with the instructors about my physical issues so they knew why I might skip certain things and so they could suggest modifications for me. Later, I weight trained, in a twice weekly group class for women, then on my own. I joined a cancer survivors rowing team, then a community rowing club. I did low impact aerobics (alone, with videos). I hate to swim, but I took adult learn to swim classes (rowers need to swim). I started taking spin classes in rowing off season.

But through all this, I stayed obese . . . through 13 years of this. Yes, I became much fitter, and episodes of pain or discomfort became less frequent or severe as a consequence.

In 2015, at age 59, something clicked - health issues! - and I decided to lose weight.

What did it take? Eating less - specifically, eating less than I burned: A calorie deficit. (No significant change in workout routine.) No weird restrictive "diets", just foods I enjoy that are tasty, nutritious and filling to me, in reasonable portions.

I lost about a third of my body weight, 50+ pounds, in just less than a year, rapidly at first, but slowing as I went to keep the loss rate healthy. I've been maintaining a healthy weight for nearly 2 years since, eating the same way.

The weight loss reduced stress on my joints, and reduced systemic inflammation in my body. Pain or discomfort aren't completely gone, but dramatically reduced and quite rare. Formerly high blood pressure is low normal. Formerly high cholesterol and triglycerides are now solidly normal.

I'm now 62, and fitter than nearly everyone I know who's my age, not to mention a lot of people decades younger. I'm at a weight in the upper 120s at 5'5". I feel great.

TL;DR - What's my point?

* You can get fitter at any age, from any starting point.
* Ditto for weight loss.
* Doing either of the above requires choices. They aren't always ones that feel emotionally safe, easy or comfortable.
* Doing either of the above, though difficult, will improve your life. Doing both will transform it.
* Exercise, by itself, does not cause weight loss.
* Persistence is really important. Most of us are better at persistence at our age.

Best wishes: You can do this, if you want it!