Exhausted just watching

When we first put the bird boxes up a few weeks ago we had a little interest but then we didn't see anything for a few weeks and thought the Blue Tits had found better accomodation elsewhere, but today we watched this little bird fly backwards and forwards over and over again from the feeder and straight into the box. It was exhausting to watch. The extra is exiting form the box like a little super man not a good quality shot but rather amusing I thought.