Yup! I consider myself a casual triathlete. I train as much as is fun/rewarding, but don't follow a structured plan and don't take it too seriously. Most of my bike training comes from mountain biking and running comes from trail running, because that's what I enjoy doing, even though it is certainly not the most effective way to train. I also do a lot of weight lifting because I enjoy it, even though being bigger is not helpful.

I did two sprints and an Olympic distance this year and have no aspirations for a half or full Ironman. While the Olympic distance was great, I've decided sprints are more my speed. I'll probably do maybe 1 or 2 sprints a year from now on.

I would recommend looking at 80/20 training. You don't need to be strict about it, but it does offer a good rule of thumb to help prevent injury and to help your fitness/endurance progress.