Since living in Panama eliminates people who are afraid of change or who don't like adventure, you're already with a like group of people. The next step is easy. It doesn't matter if you meet someone at the pool, walking your dog, or just because you're seated next to each other at a restaurant... if you both speak English, it's perfectly natural to start a conversation.
There is so much to talk about with other expats. We compare pricing of basic services, we discus favorite restaurants, and we bring up interesting solutions to unexpected problems. It's very common to talk about what things cost with someone you just met. This is unheard of in my circle of friends in the States. I would never ask someone how much they paid for their car or what they pay their maid. Here it's a matter of courtesy. We're all living in a new culture, so finding out how much it costs to get a decent used car can be a godsend. Asking what a friend pays for a maid isn't being nosy, but rather it's giving you valuable information.
Aside from meeting other expats by chance, you can join activities you're interested in, just like you would at home. I belong to an expat dinner group, an expat book club, and an expat networking group. Not only have I made friends from the US, but I've also made friends from all over the world, some of whom I'll stay friends with for a very long time.
If you're worried about not having any friends in Panama, don't be. Making friends with other expats in Panama is so easy that within a few months, your social calendar will be overflowing with social engagements.