A mistake might not be a mistake. You might think you should have done this or shouldn't have done that. But it would be better to ask what advantages your already-done deeds give you and exploit them in the present.
The architect Bonano erected a freestanding bell tower for a cathedral, but he made it on soft subsoil — a bad mistake which made the tower lean over. That mistake created a large tourist industry and put the town on the map. Almost everyone in the world has heard of the leaning tower of Pisa. Galileo conducted his famous gravity experiments from the tower. He was able to use that tower because it was leaning.
The compass and its use in navigation was developed in the Mediterranean because the sailors had several disadvantages: the water was very deep, the winds varied a lot in the winter, and the skies were usually overcast. So you couldn't reliably navigate by sounding, by the wind, or by the stars. Those were the three ways sailors all over the world used to navigate.
In the Indian oceans, they have the monsoon winds which are so regular (they change directions with the seasons) you could tell where you were headed by noticing which way the wind was blowing. And they had clear tropical skies so they could usually navigate by the stars.
In Northern Europe, they are on one of the continental shelves of the Atlantic so the water is shallow enough sailors could drop a lead weight attached to a rope to the sea floor to find their depth, and thus could tell where they were by how deep the water was. This was called "making a sounding," and it was a fairly accurate method of locating one's position in charted waters.
But the sailors of the Mediterranean had to develop some way to navigate without shallow waters, clear skies, or predictable winds. And because they had to develop navigation by compass, Spain, which borders both the Atlantic and the Mediterranean, was the first to find and colonize the New World. Without having the know-how to navigate by compass, nobody in their right mind would have sailed across the Atlantic. There would have been no guarantee they'd be able to find their way back without a compass. They'd have no familiar landmarks, no soundings would work, wind directions would of course be unknown, and whether or not they'd have clear skies was unknown.
The disadvantage of having to sail the waters of the Mediterranean turned out to be quite an advantage for Spain.
But of course, given the mind's natural negative bias, I'm sure most people of Spain assumed their sailing conditions were only a disadvantage.
So what are you going to do with what you think is a disadvantage? What are you doing now? Aren't there things in your life right now that you consider a disadvantage? Aren't there conditions you "know" are bad? That you wish would go away?
Choose one of these bad things and ponder this question about it: Could this be an advantage in disguise? Or could I make an advantage out of it? If you don't want to ponder this for weeks, do a little concentrated pondering. Use the problem solving method. Write the question at the top of a piece of paper, "What is good about this?" And force yourself to come up with 15 answers. Write them all out.
Then take another piece of paper. At the top write, "How could I turn this into an advantage?" Make yourself come up with 15 more answers. At the end of this exercise, which will only take you an hour or two, your perspective on the "problem" will be tremendously altered. The "problem" will have lost most of its power to bring you down. This process can undemoralize you. It can give you strength and effectiveness and even good feelings.