By now, I have spent more than half of my 15+ year professional career as a remote employee. My first job, back in 2000 was as a developer working for a Boston-based company from my apartment in upstate NY. We exchanged source code via CD in the mail, used a telephone and screen shared with Microsoft Netmeeting. That... was hard.
Several companies later, I find it actually difficult to work in an office environment. I'm not a hermit or even a strong introvert. I enjoy the company of other people from all walks of life, but there are so many distractions in an office environment that prevents me from doing my best work. As a Technical Operations engineer (SysEng, DevOps, SRE, or buzzword-dujour), most of my work is contemplative and best performed away from a keyboard. At home, I am free to work while running, walking, or sitting in the bathtub (TMI) with no fear of judgement from my peers. When I do need access to someone, I have a variety of tools at my disposal to suit the required latency and interactivity of the conversation.
Plus, pants are optional and slippers are the prescribed footware.
There are always challenges, though. For me, strict enforcement of work hours is a must. Sometimes I still get in the zone, lose track of time and work late, but usually I sit down around 9AM and take off around 5-6PM. Otherwise, work takes over my life and I end up neglecting my responsibilities as a husband, father, and homeowner. I am lucky to have a wife who understands my work boundaries and children who have never known a father who leaves the house for work each day. "Daddy is working" is enough for them to get them out of my office. Oddly, I grew up in a similar environment, as my father worked from a home office when I was a kid.
The biggest challenge for me has been while working for a medium-sized (1000+ employee) company in a Director role for a mostly colocated company. As an individual contributor, communication with my team and boss is relatively easy, but as a leader it is incredibly difficult to inject myself into important conversations via chat and email when those people are literally sitting next to each other. Having trusted "spies" within the organization that will keep their ears open and report back is a must or else you end up completely out of the loop.
Having worked primarily at colocated companies where I'm in the minority as a remote employee, I'm very excited to be joining an established remote first company next year and seeing how they do it in the "big leagues."