There are several hiking groups in the SF Bay Area. The SF and Loma Prieta Chapters of the Sierra Club are a good place to start looking for a group to hike with. Most who are just beginning to hike might find most of their hikes challenging. Start out with a hike that is one level lower than you believe you can hike. It is better to be too fast on your first hike than lagging behind and having everyone waiting for you!