Having goals and plans is a very effective way to achieve progress
and experience happiness in perusing worthy ideals and goals.
There is an art and science in "right-sizing" the goals, and that can be learned.
"Make no little plans; they have no magic to stir men's blood and probably themselves will not be realized.
Make big plans; aim high in hope and work, remembering that a noble, logical diagram once recorded will never die..."
- quote from Daniel Burnham (an architect and urban planner)
That is to say it is best to have ambitious, challenging, goals.
On the other side, if a goal is too challenging, it is self-rejected and not helpful.
A good goal is one that you can believe can be achieved if you work very hard. The magic number is "4% above your current maximum ability"
There is a real science behind this, it is not just a belief.
Ambitious! (+4%!) to inspire, this is my innovation :)
Realistic, for challenge to match skills
Time-bound
The key difference with "next best" diagram below is that smart goals should step into anxiety zone. It is a subtle but key distinction. To improve, one needs to cross the current limits!