Teamwork & leadership are highly valued
I bring up the careers these individuals have obtained post-postdoc to demonstrate that the leadership and teamwork experience one gains from working with a community organization or group looks great to potential employers. You don’t have to get involved with your local Postdoctoral Association (though the NC State PDA is always looking for volunteers) to find volunteer opportunities that can be useful for you both personally and professionally.
Like communicating science? Why not volunteer at the NC Museum of National Sciences in downtown Raleigh? Interested in a career in medical writing? The American Association of Medical Writers has a local chapter based here in the Research Triangle. Other local organizations to get involved with (that I am aware of) include the International Society for Pharmaceutical Engineering with both an NC State and Carolina-South Atlantic Chapter, North Carolina Regulatory Affairs Forum, entrepreneurship programs, and a host of exchange groups in a variety of life science areas.
Volunteer in your community to hone your skills, meet others, and give back
It is critical to your mental health to seek out activities beyond your lab/research work (or any work, really). Volunteering in local organizations can provide you a broader community of social support and sense of accomplishment in the work you do in them that is independent of how things are going in your graduate or postdoctoral work. You can use volunteer opportunities to work on skills outside your comfort zone and try bold things without your performance being tied to your current salary or stipend.
Prototyping potential alternative careers can be very helpful as you explore what to do after your graduate school or postdoctoral training. Getting involved in specific activities that allow you to pursue a line of work you might be interested in will help you test them out as a potential career path for you. You can self-reflect during these activities asking: do I enjoy doing this?, do I need to hone some skill before seeking formal employment in this area?, etc...
By venturing outside your school/work, you will also meet a more diverse group of professionals and start to learn about the many career opportunities out there in the world.
Just a few months into my role in Postdoc Affairs at NC State University, I sought out opportunities to serve on various committees in professional organizations relevant to my career: the National Postdoctoral Association (NPA) and Graduate Career Consortium. Working on committees tasked with resource development, education research/outcomes assessment, and bench-marking of career development professionals has allowed me to greatly expand my network and learn more about exciting developments in these areas. I am also part of the early conversations around how we will communicate new resources, work, and findings to our membership. This helps me stay informed on new initiatives and advances in the field...something I find immensely valuable.
I also volunteered to work with a group of individuals through Future PI Slack analyzing and writing up results from a faculty career applicant survey. While this work took up quite a bit of time on the weekends from June to October, we have submitted this work for peer review and, if accepted, it will be my first publication in the education research/outcomes area. I also plan to continue working with some of my co-authors on this work developing more detailed, future surveys to understand factors that lead to a successful faculty job search.
As I seek to grow in my new area of career/professional development, I expect all this additional "side" work to pay dividends...and perhaps they already are.
I successfully ran for the Board of Directors for the NPA this fall and I think being involved and meeting others in the field probably helped with name recognition on the ballot.
Obviously, where you seek to invest your "free time" to grow and develop will be different from my own experience but I urge you to make the time to develop knowledge, skills, and a network outside your current one. This could be in the form of going to local meet-ups focused on some area of interest to you (data science, ag tech, science communication), attending networking events to learn about other opportunities in the area, or volunteering for a cause you are passionate about.
You never know where these extracurricular experiences might lead.
If you don't take part in any, though, you'll never find out.