Watercolor Teaching

I've recently been teaching a 78 year old man how to paint with watercolors. The first time we met was on his farm - he was wearing overalls and hobbled out onto his front porch to meet me. As we walked inside and made small talk he showed me various paintings scattered about his house - he explained to me that his wife used to be a wonderful painter before she died. And he wanted to learn to paint in memory of her. In fact, the last painting she worked on was a watercolor landscape she had tried to teach her husband how to create, but to no avail.

Now he says it's up to me to teach him. Lord, help me.