Christine Climbing Tree

Went to visit Shaun (my cousin) and the kids yesterday as it was Edmund's (her son's) birthday. Edmund and Michael are my distant cousins but I prefer Sally's title for them - the little things that are not your nephews. I love the little beasts but have a bit of a problem with them - I have set the precedence that I will play with them. There is no going back on this when I get tired of them, they just don't understand or listen or care. Apparently I only ever visit Arundel to allow them to jump on me. They have pointy little elbows and knees and feet that hurt! Any advice?