You don't HAVE to leave

As I've written about here, periodically, youth group leaders should be given a chance to step down if they don't want to be a leader anymore. This exists to fight the unwritten expectation that youth group leadership is a never-ending commitment.

But, leaders often have an expiry date due to life's transitions and when this happens, the option to become a part-time leader should be explored.

But, a leader never HAS to step down.

When a leader starts working full-time, they might stop youth group leading... but they don't have to. 
When a leader finishes university, they might step aside... but they don't have to.
When a leader gets married, they might stop leading for a season... but they don't have to.
When a leader becomes a parent, they might cease being around on a Friday... but they don't have to.
When a leader turns 30 (or 40!), they might make way for other leaders... but they don't have to.

As good as it might be to give space for leaders to step aside, it would be equally as unhelpful to push them away if they're not ready.

For, while you don't have to be a youth group leader for all eternity, you should never feel that you HAVE to leave just because "your time is up", you're "too old" or "it's someone else's turn."