I like the late Bernard Haldane's definition of an achievement.
He says achievement is something you yourself feel you have done well, that you also enjoyed doing and felt proud of.
In other words you are looking for an accomplishment that gave you two pleasures: enjoyment while doing it, and satisfaction from the outcome.
That does not mean you may not have sweated as you did it, or hated some parts of the process, but it does mean that basically you enjoyed most of the process. The pleasure was not simply in the outcome, but along the way as well.