Marianne, I don't know where you live, but you don't need to be in a big metro area
to find a good coach. If you need to get limber, maybe start with yoga, but find someone in our age group who knows about rusty joints and tight ligaments! I am so lucky in our little town to have a fabulous variety of fitness professionals who are dedicated to the wellness of their clients.
Go to all the gyms in your area and interview the trainers. Make sure they are certified in whatever they are teaching. Observe a class. There is such a wide diversity of activities!
Do you like to dance? There is a great class that is very popular now called Zumba. It is a really fun latin-style cardio workout that combines movement with toning weights. FUN!! Google it, and see if you have a class in your area. I hear that about 5 million people "do" Zumba every day! We have 6 classes a week in our little gym and they are full every time. I can burn 500 calories in an hour. Class members range from high school age to 60's, and all levels of fitness love it.