Before I post what I wrote I first read it over. Even though I was careful to write everything correctly I invariably find a mistake or three. Then I correct what I wrote, spellcheck it and post. Then I read the post again and lo and behold - I find another mistake! So I correct it and repost [I wish I could fix my mistakes in life as easily].
Then I reread the post some time later and find another mistake. I think "How did I miss that?" I correct, repost and feel that this is it. Clean of errors.
Until the next time I look....
Teshuva means closely examining your deeds. The more we look, the more imperfections we will find. The gemara says that you should confess sins that you already confessed last year. A fresh look will almost always reveal if not outright errors, at least aspects that require polishing.
Example from my life: I am trying to start a yeshiva next year. This is a huge undertaking that occupies much of my thoughts and time. Recently I was approached by someone on their birthday and given a gezunte, heartfelt bracha [the Talmud Yerushalmi says that one has special powers on his/her birthday]. Brachos are not only supposed to create a better, improved reality but also serve to guide and edify the receiver. When Yaakov gave his son's "brachos" prior to his demise, he essentially told them what their task in this world is. The greatest bracha is knowing what you are supposed to become. In the course of the lengthy, ayintova-dike bracha I was told "You should build the yeshiva li-shem shomayim" [which was immediately modified by "I'm sure you are"]. This has been haunting me ever since. Am I really doing everything PURELY ONE MILLION PERCENT li-shem shomayim. As one gadol once put it "Even your li-shem shomayim has to be li-shem shomayim". I am very connected to myself [read: have ego:-)] and thinking about the complete purity of my motivations is a penetrating question that challenges and probes me to rid myself of the spiritual dross that clings to my psyche and soul.
This example was more subtle because the project of building something spiritual is basically a positive one. When I think of other more mundane actions and examine my deeds I find that teshuva is the order of the day. And after I am done cleaning up the mess I return later to find I missed a few spots...
IF a person is depressed, down in the dumps, OCD or otherwise not feeling upbeat about things, the teshuva process i described should be carried out with great care lest it have negative repurcussions. I was writing for happy, healthy optimistic types who can take a licking and keep on ticking:-).