In 2007, an Auckland club, Auckland TC, had very few younger members.  The mission statement of the club said they should meet the needs of trampers.  Hence the trips officer decided to put on trips for under 40 trampers and under 25 trampers.  A naive and direct approach, and it attracted no criticism from club members.   A web search found such tramps are run in the UK and are a great success.
Something was put on the website that non-members could find with their search engines, and it went into the club monthly magazine.   Readers found that the club offered day tramping trips exclusively for people who are not yet forty years old, and also for people under 25.  They read that two advantages of a club were that  it provided a hut at Ruapehu to snowboard, ski and climb, and it provided a club bus to do trips from A to B, which is so much easier than organising car shuttles.
The first under 40s trip had no takers at all, and the leader joined another group.

  The Auckland University TC  emailed their members about the first under 25s tramp.  It was attracted one person beside the leader and his cousin. 

There was a second under 40s tramp on 22/7/07.  Four people went on it.  The stream was too deep and cold, so they joined up with the other ATC trampers.