You have two options when you hear this from someone you like and respect.
Either you decide that their wisdom, experience and perspective bring something to the decision that you didn’t see, and they are right.
Or you decide that there are things you know that they don’t know, things you can see that they cannot, and that even though it feels like 9 times out 10 you’d want to follow their advice, this time you won’t.
Either way, your job at this point is to hear the advice, process it, make adjustments, and take action with conviction. Getting stuck in between what both of you thought is almost never right, and moving forward tepidly is the worst outcome of all.