How do I grow my newly published Health and Fitness Forum?

How often are you posting? You should be writing a post every single day (or write more than 1 and schedule it for publishing. If you're unable to do this yourself, then I suggest hiring someone to write posts for you.
It's a matter of perspective. If you're a skilled writer, then it's a question of time, and if you don't have time, then weigh up the cost of outsourcing.

Try Google ads and see if that helps.
Check out sites in your niche and see if you can post articles or replies if they have conversations and comments are allowed.

Have patience because it takes time to build a successful business.

I would do more marketing, and then setup a lead capture mechanism on your forum so that you can notify people when new forum posts are published. Forums are a catch 22. People want to interact on a popular forum, but if a forum is new and lacking activity and content, it's hard to catch the attention of someone who lands on your forum. You will have to do more than just 2 blog posts and 2 youtube videos.

Promote your forum hard everywhere like you would do a $500 product. Participate on related forums, continue to reach out to blog owners for guest blog posts, put a hover ad on your forum to capture email leads when they land on your site, create Youtube videos about various health & fitness topics, participate in cheap paid advertising, find ways to monetize your forum, write more blog posts on your own platform with proper SEO, and participate on social media - with an emphasis on Pinterest.

Join groups on Facebook and share helpful information, and drive traffic back to your forum. You should even start your own Fan page also that you can populate with updates about new content made on your forum. And make article-style posts yourself on your forum. It's content. These should get you up and running as a beginner starter plan.

Instagram would be a good start... Gary Vaynerchuk's $1.80 strategy would be a way to accelerate that.

Treat the forum as a blog... go deep dive into some content ideas and to help draw search engine traffic.

2 blog post and 2 videos... is effort, but not success... get in the double digits and still no traffic then you MIGHT get concerned.

Just pump content - it will come, Rome was not built in a day and either will your Forum. Think of it as nation building ( for your tribe ) patience - and time - put in the work to get the results.

I will assume you lift weights? I worked out my arms for 2 days and still no results...any suggestions? Not being mean here - I get it... just putting it into perspective for you. Anything you build on he web will directly reflect your efforts to a healthy body - takes time.

Hope that Helps!

Well you cannot expect to publish some posts and go on top ,with a forum its hard work and you need to make posts daily .Also you need to advertise your forum with paid traffic,in the beginning its the hardest but if you take it from tbe ground then it will grow alone

Hello Mohammed MX, Appreciated your work and the way you spread your experience about health, and fitness this is beneficial for our community, Please make a forum and share more of your experience here.