A fitness site can have numerous revenue streams. Create healthy eating plans and recipes and lock them away as premium content. Promote and sell a fitness training course, eBook, or a series of videos. Or advertise your own personal fitness services on your site. Topfithub is a good example of a fitness site with decent video content alongside product reviews.
You can sell affiliate stuff if you did not use the stuff but a high, high, high, really high level of clarity is required to do this. Most bloggers lack this clarity. I recall Tony Robbins selling/being an affiliate for a $25K coaching class. Never took it. Never sat in it. But the guy made millions. He had full clarity in selling without seeing. So he rocked out the selling.
Similar to a YouTube vlogger, if you have a large following on Instagram then you could become an Instagram Influencer. You will be paid to promote products in your photos, from wearing certain clothes to action shots of you using particular merchandise. As your Instagram following grows, you may start out simply receiving freebies in return for a picture of you with the item in shot. However, for those with followings running into millions, you can expect large payments to display products in your pictures. Use sites like Hype Factory to help connect you with companies prepared to pay for your influence.
For those with a large Twitter following, you can make money from your Tweets alone with Sponsored Tweets. You could be paid for sharing a business’s information, recommending restaurants or hotels, or tweeting pictures of you using or wearing products. As with all sponsored posts on social media, businesses will only be prepared to pay you to Tweet if you have a large following that you can influence. So work hard on building up a loyal fan base.
If you have pop-ups and optins on every page, I would have to think that it would be a lot harder to convince someone to link to it. Especially since the pages where you have your optins (and probably receive the most traffic) are probably the same pages that you have your best content on as well that you'd be hoping to pitch in your outreach campaign.