A friend of mine recently asked how I'm able to train by myself everyday. And I think my 14-year-old self would've asked the same exact question.
Starting out in endurance sports, I couldn't find the motivation to run or swim by myself; I needed someone to run with (or have my mum bike alongside). With swim, I always swam with a team or with friends in the off-season. I rarely trained alone. Even when I started training for triathlons, I did all of my training with the triathlon or cycling team.
I only started training alone in last year when I had more specific training rides and run on the weekends, and I lived further from the main campus. It was only after graduation when I moved back to NH that I started training alone full-time. While training alone has its benefits, it wasn't really done by choice. at least not at first. If there are any group rides or runs near me, they happen during work or class. I'm also located in an area where cycling and triathlon teams are few and far between. Plus, it's hard to organize rides with friends or people who ride at a similar pace as you (especially when they live a 40-65 minute car ride away).
Do I like training alone?
Yes, mostly...kind of? It depends.
With biking and running, I've grown to prefer training by myself. Even though I would like to do easy coffee rides with friends, I want to follow those specific workouts, and I like being in my own head when training. As a triathlete (even as a cyclist), you will end up racing against yourself, and sometimes by yourself. Might as well use your training to train yourself mentally for those situations.
Now, I wish I could the say the same thing about swimming, but swimming is different. I've noticed that I need to swim with a group, or at least one other person. I enjoy being in the water. However, sometimes it makes me too complacent, and I don't really do that actual effort I'm supposed to do. On top of that, there are many days were it's difficult to motivate myself to go to the pool. In a group setting, you have the peer-pressure (in a good way...usually) to show up to practice.
I'm incredibly lucky to have access to a gym with a pool, but the gym I use doesn't have an adult swim group or team. Affording to be on a master's swim team is an expense that's not personally feasible, nor does it line up with my schedule and commute. In an attempt to be somewhat fiscally responsible (or at least as fiscally responsible as I can be as a student/triathlete...), I opted out of a swim team and do my swim workouts on my own.
So, by yourself or with others?
In a perfect world, the best option would be to have both: do the specific sessions on my own, do those coffee rides or runs with a group, and join a master's swim team. Then again, it's not a perfect world and you do whatever floats your boat (and your wallet). At the end of the day, it's what you make out of your training and the resources that you've got.
Happy Training!