The following is a small sampling, based on the shmooze of Shvi'ee Shel Pesach 5759
The Chozeh Milublin, The Beer Mayim Chaim, R' Hershele of Ziditshov, R' Tzadok Hacohen and other tzadikim said: When a person feels "I blew it already - I messed up this time, and still he doesn't give up, he keeps trying to salvage what he could - ignoring the fact that he already failed (R' Tvi Meir calls it "Kum B'palgus Laila" in the words of the Zohar Hakadosh) then the Nachas Ruach that he makes for Hashem, is greater than, when one is completely successful.
This is the epitome of Shechina Bitochtonim, which we know is the purpose of creation.
It is the greatest form of mesirus nefesh, because it is completely against human nature, as there is no short term satisfaction.
The yesod is hinted to, in parshas Vayishlach. "Vayeiavek ish emo ad alos hashachar" Chazal say "He'elu avak ad kisei hakavod" R' Tzvi Meir says that it means that by this struggle that Yaakov Avinu had with the samech mem, he made the greatest nachas ruach out of the dust of the earth - the lowest situations.
[This is in keeping with the pushut pshat. We don't find any hint in the pasuk that Yaakov overpowered the malach. On the contrary the malach actually wounded [i]him[/i]. But just because Yaakov wouldn't give up even after he was wounded, the samech mem was forced to "agree" to the brachos - which is a "siman" to the tikun hashalem that will come through our not giving up]
Perhaps the greatest illustration of this, is by Yoseph Hatzadik. The gemoroh (in sotah 36b) says, that Yoseph actually came in to Potifar's house to sin (as Rashi brings) Then the Gemoroh says that he actually spilled seed at the time, thereby losing Ten Shevatim that were supposed to come from him. And, when after all that, he held back from sinning, he became the Merkava for Midas Hayesod and one of the seven "Royem".
R' Tzadok and other tzadikim explain that this is what really constituted the nisoyon. The menuval said to Yoseph: Don't you see that you already messed everything up. And don't you realize what a goner you are. The Shevatim have already poskined that you are chayav misa, including the Shechina Hakidosha in their Beis Din. [Even Yitzchak Avinu who knew where Yoseph is, didn't tell.] Nobody cares about you any more. You're lost and cut off in this world and the next. And now you failed so badly. Face the facts, it's over!
But Yoseph Hatzadik said no! I don't care about anything - not even about being a tzadik. The only thing that concerns me is: What do I need to do at this moment? What does Avinu Shebashamaim want from me right now? It was in that zechus that he was zocheh to everything. That is why he is called Hatzaddik. And that is why Krias yam suf was in his zechus as Chazal say "Hayam raah vayonos - ma raah? arono shel Yoseph!"