You can outgrow a goal before you reach it.
We tend to celebrate reaching the destination and explain ourselves when we leave the road. But learning what you do not want can happen halfway through a sincere attempt. That information is part of the journey, not proof that you should never have started.
Pause before deciding whether to continue. Are you tired of the work, or no longer interested in the result? Those are different problems. Rest may help with the first. An honest change of direction may be the appropriate response to the second.
Do you need relief from the effort, or permission to reconsider the destination?