If you achieved your personal goal in life did it actually make you happy or did you just find another goal?
The question in and of itself leads me to ask if you think that achieving a goal might, could, should or would bring happiness.
Happiness comes from within. When we think, “when I achieve X, I will finally be happy" if that is the thought process then reaching the goal will always be lacking in satisfaction or the good feelings won't last long.
But if the question is simply, you finally hit every life goal you wanted to, what did you do next? I have yet to achieve everything I have set out to achieve, and I know I will simply find new experiences to have. The world is vast and in this lifetime I could never do everything I want to. Also my life goals change every year as I level up on my views and change and grow as a person.
Not sure if that answered your question.