When I met this family the morning of our shoot, the girls were a little bit shy but enjoyed throwing rocks into the lake, and climbing around with their Mom and Dad.
At the end of our session, both girls hugged me multiple times and asked me not to go.
Parents often stress about their kids cooperating during a session, but I always assure them that it will be okay. All kids find it a little bit weird to have someone following their family around with a camera, but it never takes very long for them to forget that I'm a stranger and I get to capture their true happiness.
My biggest advice to parents would be not to worry about what the kids are doing and to just enjoy your time together and they'll warm up too.