When is the last time you deliberately took a risk and stretched yourself?

For me, it was launching my first business a few months ago. I am learning a lot so far in this new territory; time will tell how the rest of this story goes. Before that, about 15 years into my Air Force career, I was feeling burned out. I had been working as a clinical psychologist in a clinic for seven years and was ready for a change of pace. If I did nothing, it was going to be more of the same for at least another five years to be eligible for a military retirement. Ultimately, I chose to apply for a post-doctoral fellowship and was accepted. 

I was excited, and also intimidated. This career shift required me to learn a lot more (and quickly!) about a related, yet different field of industrial-organizational psychology. I also had to sign for an additional service commitment, taking me at least one year beyond the original plan to retire at 20 years of service and potentially adding more strain for my family. I also was told that making this change at that time could prevent my next promotion, but I decided I was willing to take that chance. As it turned out, I ended up experiencing the most rewarding last 5 years of a 22-year military career. I was also a better leader, coworker, wife, and mother for it. And the icing on the cake: I did get that last promotion. 

What opportunities are out there for you to take a risk or make a career/life change?