That market is saturated, but there are ways to stand out in that niche.
I've mentioned before that I work on flexibility training mostly, but I also do a lot of strength training. I'm always interested in finding new channels because everyone has unique ideas and approaches on how to exercise. I haven't watched some of these channels in a while as I no longer find their advice as useful, but here are my thoughts on why some of them have unique ideas.
- Pigmie are really good for finding experimental ideas. He usually tries something more unorthodox out for a week and shares what he did and the results of it.
- MovementByDavid is good for general flexibility advice, but I find him kind of annoying. He has a very interesting way of filming his videos that comes across as hyper, but keeps your attention, whilst he goes over what he's talking about.
- StretchandTrain is another good one for flexibility. She started flexibility training at an older age, so I've found that she understands what it's like to start as someone who's very inflexible. After all, a lot of the people who do flexibility channels were put in gymnastics at an early age and have no idea how they got to where they are.
There were others I tried watching, but found the advice to be useless as the YouTuber was generally just showing off or trying to post annoying hornybait content.
Weight loss is a big thing and sharing advice on how you not only managed it, but kept the weight off is something many would find useful. The same goes for lifting weights: if you feel you have a unique approach to doing it, then I'd say give it a go. If anything, starting a channel is a good way to document your progress for others to learn from. Even if you don't get a million subscribers, I'm sure you'd still be helping someone, or at the very least, helping yourself.