There's one issue I suppose have to handle a bit: is a self-improvement project a good idea at all?
The first obvious argument against self-improvement projects is that the manuals, self-help books, are harmful bogus. An especially garish example is Rhonda Byrne's The Secret, which basically promises to show you how to cure yourself of farsightedness or cancer by the power of positivity, or something. The less obviously harmful side of self-help is that they tell you that you can be or achieve anything. When you obviously fail to become CEO of a megacorporation in a year, the fault is your own. You should just have been more positive.
Still, the size of the self-help market or bad self-help books are not rational reasons to forgo improving yourself or even using (good) self-help books for help.
Why improve at all?
The more interesting argument about self-improvement is some sort of a buddhism-flavoured idea about contentment and accepting yourself. If you always want to be a little thinner, little richer or more succesfull with the other sex, you will never be happy. Self-improvement is another endless and ultimately empty Western addiction, like always buying more cars or breast implants. (See for example Quashing the Self-Improvement urge.)
Rather than feeling bad about yourself and always trying to improve, you could try just being happy. Feel amazing about everything that is happening, instead of always running after the next goal.
The latter argument is naturally quite powerful. Its weakness is that it's applicable to anything at all: self-improvement just among everything else. If you are not happy about where and what you are, there are no guarantees that you'll be happy anywhere else either. No matter what kind of abs you have or how many supermodels you date at the same time.
The question is: if you are an unhappy person and you want to become a happy person, is this not self-improvement also? General happiness of a person is probably somewhat given, but I think it has to be a skill also. Learning to accept yourself and being happy about the stuff you are.
This viewpoint naturally soils the "stop improving and instead magically start being happy" -idea. You would still need to learn, practice and change yourself from an unhappy, imperfect person into a better one. Still, would this be as down as the turtles go in this case?
My reasons for self-improvement
Happily, I'm a happy person to begin with. I'm quite content about everything, but I'm also curious and like learning. Self-improvement seems like an infinitely interesting project. I won't probably have many traditional self-help goals during this project. I have as much friends, abs, work and girlfriends as I want.
Structured challenges on the other hand are always welcome. A self-improvement project will offer me a practically infinite amount of stuff to test and research and it will assuredly leave me knowing more about myself than ever before. In addition, I've already found a brilliant blogging platform, learned a bunch of Swedish, and vacuumed the apartment twice, so all sorts of good stuff seem to happen rather automatically at the side too.
There are my explanations. Are you convinced, what are yours?