The demand for trade skills (plumbing, carpentry, electrician, construction, mechanical assembly etc.) is growing as more and more people gravitating toward white collar jobs. These are also a nice skill to have in your daily life. You don't need to think of these skills as "backup" career plan but more of something that takes you away from the work you do for 8-10 hours a day.
Though HN is not fond of him, you might want to check out Mr. Money Mustache http://www.mrmoneymustache.com. He was a software engineer and "retired" at early age and enjoys his carpentry and construction work. The forum on his site also offers wealth of information on alternative methods of keeping busy that also pays.
I'm in now or I wouldn't recommend it otherwise. Pick 35P or 35Q in the Army. For 35P, you are basically a student for 2 years and if you're good they'll send you on an all expense paid vacation to Africa, the Middle East or China (for a language immersion). You can learn an entire foreign language from native speakers while you collect a paycheck and support a family. As 35Q you would get to do network security stuff.
Do not join if you can't get a good MOS. Joining as say, a truck driver, will not be a good time for someone who frequents HN, I can promise you that. Not because of the job, but because of the people you'd be around all the time.
Now, just try to keep your current job and you'll be golden.
Adjusting one's lifestyle to decrease expenses is a much better way to "create" wealth.
I thought the average return just from the stock market was 7%.
I am a total novice, and have fairly little invested, but those are the sort of numbers that pension projects are based on.
If you can keep you personal burn rate low, and over time invest a significant amount of money at 5% return for 10 years, the interest really starts to snowball.
If the average return from an index fund is 7% and inflation is, say, 3%, then you're making an extra 4%.
If you're investing $100k, you'll double the value of your money in 20 years. That's not great for someone who doesn't have much other cash and could use that $100k over those 20 years for significant lifestyle improvements.
In the investing world, index funds are very useful, and they often beat inflation by a few percentage points. But that return is only significant when you have tons of money.
As I pointed out in another comment, turning $100k into $200k (adjusted for inflation) would take 20 years, assuming index funds grow 7% every year and inflation is a constant 3%.
But if you have, say, $100k in income and $100k in the bank, you're going to "make" far more money by decreasing your costs by $20k than you could by investing that $100k (on average).
Obviously there are people who get lucky buying houses and whatnot, but no one can reliably double $100k in 5 years.