The bigger your goals, the longer it takes to achieve them, and ambitious goals should not be easy, by definition. At the same time it's important to make sure your goals are challenging, but achievable. Once you set the goals and are working on them, it helps to set check-in times and evaluate your progress. If you are making a lot of progress, perhaps you did not set goals high enough. If you're stuck, maybe it is worth it to scale down.