Yeah, Roody, the phrase "invest in yourself" has been co-opted by the education establishment to imply accredited degrees, certifications, multi-year programs, giant student loans, etc. You know, all the stuff that only they can provide. Those are all good things, but I specifically meant learning immediately useful skills in bite-size chunks.
Now about retirement. Everyone knows of some retired guy who's turned into Mr. Fix-It / Mr. Gardener / Mr. Chef. One reason this happens is, they can save a bundle of money and have a good time doing it. A person does need a certain amount of money income to retire, but the idea is to sharply reduce the income requirement by satisfying your own needs as directly as possible with ingenuity and labor -- which is precisely the Do It Yourself philosophy. You can do a little or a lot. One great thing about this approach is, it's not just for the retired. It's helpful for anyone who "has more time than money", as they say. It's not a complete solution, but nothing else is, either.