Why not become a Group Leader?
Being a Group Leader is a very satisfying and interesting role. If you have a talent or special interest in a particular topic, it is very rewarding to share this with other people. In u3a the situation is far more social and relaxing than in an educational situation.
A great deal of enjoyment can be had by members learning something new or improving a forgotten talent, perhaps learning something you didn't have the time to do when you were working. One of the joys of retirement is having the time to do new things and meet new people. Being a Group Leader is all about sharing your knowledge and ideas and having fun.
There is another way of becoming a Group Leader, if you feel you do not have any knowledge to pass on - form a group and find someone with a talent you would like to learn and they can share their expertise with the other members. Please do not feel as though you have to be an academic to lead a group! Ideas come from the members which you all share together.
The social side of a group can be very attractive to many members. Having a break in the activity, or ending the meeting with a cup of tea/cake, helps members make new friends. Give it thought and maybe encourage a friend to join you and assist you in starting a new group. It will be fun!