Mental Stimulation?

Is it better to have your loved one try and do things themselves to help stimulate their minds as long as they are not getting frustrated or is it better to do things for them?  My gma tries to cut her food and she never gets frustrated when she does it, in fact she is quite patient as she is sawing away on softer foods such as chicken.  But watching her slowly making her way thru it makes me want to help her.  Sometimes she will let me and other times she won't.  So is it best to let them use these "excersizes" to help stimulate their minds?

Gma likes to set the table too (even though after she leaves the kitchen I have to redo it) and my hubby tries to help her. So I usually have to slap him away and tell him to let her do it. That it helps to stimulate her. My hubby tries to do everything for Gma that I have to remind him that if she doesn't do it herself, she may forget how to do it. Even though I know eventually she might anyway. I found this out the hard way. One time when she came home from the hospital and she was a bit weak, I was making her breakfast and bringing her coffee. Well when she was better, she would sit on the couch in the mornings - waiting for me to get out of bed (sometimes 2 hours or so after she had gotten up) and give her coffee when I knew she was capable of doing it herself. So I had to sort of "retrain" her to get it herself again so she is not waiting on me.

Washing hands - lol yeah, Gma has trouble with that too. Of course some of that might be her eyesight since she is almost blind. But she will go in to use the bathroom, she says she washed her hands but I can tell she didn't because if she had a bm - sometimes she misses and it gets under her fingernails. So then I have to take her in there to rewash her hands with a nail brush. Sometimes it's like having another kid in the house :0)