How much activity and exercise does my mother need?

Background: My mother has been living with me for almost one year. She had a stroke 15 months ago and lost about half her vision due to blind spots. Before the stroke she was a designer and worked on the computer all of the time. Since the stroke she has been retired and cannot work or drive. Due to her vision issue, her balance is a little shaky. She walks around the house fine but when we go anywhere we walk arm in arm. She says she can’t use a cane or walker. She is also a little forgetful since the stroke and gets easily distracted. I try to let her eat on her own schedule but sometimes I worry she won’t realize she is hungry. I feed her breakfast and dinner on a regular schedule but leave lunch up to her. She mostly watches tv all day, naps, or gets on facebook. She has puzzles, books, art things, even quilting things if she wants to do them but she says she isn’t inspired to do them.

We go to her old employer’s office once a week because I am now doing some work for them. Then we see my sister and her two toddlers for a few hours. On Saturdays and Sundays we go shopping or to the beach or to a movie. And we eat out at least three times a week. We probably run other errands once or twice more a week. But I’m not sure if she gets enough stimulation or movement. She takes a shower almost daily. She unloads the dishwasher each day and walks from her room to the kitchen for each meal and then back to her room. It is too hot to walk very far outside but I wish she would walk in the back yard which is fully fenced.

She says she is contented. She also says she doesn’t really want to do much and any friends she had before are all too far away to visit very often. She says she will call them but she procrastinates calling them for days.

I worry that she isn’t getting enough stimulation. Or exercise. I work at home but can’t continuously tell her to do this and do that, then remind her to do it, or take her outside in the heat. I wonder if I am doing enough. There are three or four days a week when I don't plan things for her and just let her entertain herself. I still cook or get take-out for every dinner and cook breakfast every morning and we usually watch tv for 1-3 hours about 5 evenings a week.

Does she need me to make her do more?