My 4-year-old son tends to default to saying no changes in activity (even if he is clearly no longer interested in the current activity). Overall he is helpful, considerate, and will do things we ask around the house but he will just generally dismiss any proposed activity if it isn't the one we are currently doing. This is even true for things that we know he likes and has done before (e.g., going to the pool).
Generally we can get him to go along with some cajoling but the ensuing battle will often take on a life of its own independent of the conflict. Further, it doesn't seem a battle is the best approach every time we want to do something.
I don't expect or want blind obedience but rather for him to base his opinions on a genuine consideration of what we are doing not just defaulting to no.
What is a more constructive way to approach changes in activity to avoid default contrarianism.