Don't make it too gentle. A friend of mine went for a trial lesson at the age of 70, having been meaning to learn to fly for many years. I guess the instructor took her to be your traditional little old lady, which she definitely isn't. After what sounded to me like a very gentle little jaunt around the local area she told me she was disappointed; she thought it was too easy and she'd soon get bored. I finally convinced her it wasn't all like that! She's now done a good few hours and is enjoying the challenge. Appearances aren't always what they seem.