I would throw in some caution here: if your spouse works at the same company, or in the same industry as you, you are not diversified, and should something happen, you could be in a world of hurt.  Companies do go out of business, companies do lay employees off.  There is nothing wrong with working together, but realize that you are not diversified and you should be trying to maximize other income streams as a result.
Another source of income (or at least revenue) can be selling things you no longer use. When we go through our closets and drawers, I tend to find a lot I can do without. Some goes to Goodwill / Salvation army / Habitat Restore (tax deduction = income), some is resold on Amazon or eBay, some goes to the trash. I’m not sure if reselling something you paid more for should really count as income, but it’s money in the door, or less money out as is the case with donations.

became $1,000,000 during an 18 year period (about 3x better than Berkshire Hathaway). Five – ten shares, or more, invested in a ROTH Ira and held *consistently* come h..l or highwater, with dividends and splits reinvested, may provide you a very pleasant surprise in 20 years or so. Asset Managers often do better than the assets they manage. Eaton Vance (EV) and T. Rowe Price (TROW) also did exceedingly well over a 25 year period.

Joe started Retire by 40 in 2010 to figure out how to retire early. He spent 16 years working in computer design and enjoyed the technical work immensely. However, he hated the corporate BS. He left his engineering career behind to become a stay-at-home dad/blogger at 38. At Retire by 40, Joe focuses on financial independence, early retirement, investing, saving, and passive income.
In 2017, I ended up deploying roughly $611,000 into stocks and $604,327 into municipal bonds. The stock allocation should boost dividend income by about $12,500 a year, and the municipal-bond portion should boost income by about $18,000 a year after tax ($26,000 pre-tax). Therefore, total passive income gets an about $38,500 lift, which recovers over half of my $60,000 loss from selling the house.
5) Determine What Income Level Will Make You Happy. Think back to when you made little to no income as a student. Now think back to the days when you just got started in your career. Were you happy then? Now go over every single year you got a raise or made more money doing something else. How did your happiness change at all, if any? Everybody has a different level of income that will bring maximum happiness due to different desires, needs, and living arrangements. It’s up to you to find out your optimum income level.
As an struggling young Engineer (back in the Carter era) I bought anything I could renovate then rent to justify paying the 18% interest. I never took vacations but worked on my properties all in the pursuit of passive income. I drove junk for many years & many months I just got by on credit cards. My friends & colleagues were amused by my ‘stupidity’ but most are still working to make enough for retirement.
These are just a few ideas to get you thinking about what you can do to create a multi-streamed income. Your project might turn into a full-time job in itself or it could just be a back-up plan that gives you peace of mind while you continue to work a day job. Finding extra work that you really enjoy can be a great way to share your skills, meet new people, and take your personal finances to the next level. 

Andrew Rafal, Founder and President of Bayntree Wealth Advisors in Arizona, recently told me about his push to get clients to diversify their income streams. The Great Recession feels like an eternity ago now that the economy is looking up, he says. The job market is strong and consumer confidence is through the roof. As a result, it’s possible people are getting a little too comfortable.