The biggest help for me when when my children acquired much younger cousins. Getting rid of anything was anathema, but sharing it with the younger cousins was a delight. Got any siblings you can put on the job?!
Sadly, DH and I are the last to have kids so ours are the youngest. Worse yet, DS wants to keep the stuff to pass along to his own future children!!
As for the recycling truck, I can only use that option selectively. Once he has paid more than passing attention to the fact that an item should be kept as a souvenir, he will NOT forget its existence and will ask for it from time to time. Sigh.
