Diversify your nonprofit's funding sources, please!

I learned traditional fundraising methods during my Masters degree and from the many workshops I've attended over the years.  The one thing I remember the most from these seminars is--nonprofits need to diversify their funding sources and not to rely too much on one source of funding. However, my personal experiences in organizations have taught me quite the opposite.

In the first organization I worked for, we relied solely on individual donors.

In another organization, we relied solely on Foundation grants.

And yet in another, the majority of income came from fee for service activities.  

I've tried and I've tried to encourage each of the Executive Director's I worked for to increase other funding sources but with very little success. I've even offered to do a lot of the grunt work; however there were always other priorities.

Even though I have never experienced it, I know organizations that diversify their funding sources have a less likely chance of going out of business.

Last December, I learned that one of the organizations I worked for in the past had to layoff most of its staff because the majority of its one funding source dried up. It just hurts to think this could have been avoided.

How diverse are your funding sources?