My own ecommerce site, what to sell?

CJ is an affiliate program, not a drop shipping program. I know that are some nutrition companies out there that offer reseller/drop shipping, I would continue to search for them. Here is one site I found with a quick search that may be able to help you: AltHealthCare.com Wholelsale and Dropship Herbal Supplements and Natural Products

Keep in mind affiliate and dropshipping are two totally different things. Affiliate = someone else makes the sale, and you get commission. You don't handle customer service or anything. Dropship = you make the sale, you buy the item from someone else, and that company sends the product to customer. You handle returns, customer service, etc.

sell free samples for an profit.... good mark up

Ok since you are going towards nutrition and supplements, so i think i can suggest you is that you should have exercising machines, small ones, which people can keep at their homes with out taking too much space in the house.
You can also sell apparel for exercising, shoes, Wrist Bands, DVDs of training programs of pro gym instructors.
And since you are making an eCommerce website, i would suggest that you should have the Live Chat software with your site because Live Chat would help you communicate with your customer at all times and you would be able to keep record of what ever your customer said that what ever your customer was demanding for. Then you would be able to understand that how you can expand your business in the future.
And if you don't understand what else Live Chat can do for your website, you can PM me, we can have a discussion about it and we can also discuss more details about your site and its promotion as well.

Selling something on which you know that you can be an authority is one of the best ways to not only get potential customers to trust in you and your brand, but also gives you the upper hand when it comes to marketing.

When you don't have the budget or time to spend cash on advertising and marketing -- simply writing and talking about subject matter relating to your inventory online is a great and reliable way to build your exposure and authority online.

Sell products that are as unique as possible with low return rates. Customer service and managing the supply chain is critical to the dropshop model, so products that have variables/potential problems i.e electronics (software), clothing (sizes) etc will cause you problems.

Most folks starting out in ecommerce these days seem to be focusing on accessories - so things like mobile phone accessories, gaming accessories, pet accessories etc.

Nutrition products are EXTREMELY competitive. You better have bucks, skills and patience. It's better to find an under served niche that won't be so hard. Everybody and their dog wants to promote this stuff. And the big guys REALLy know what they are doing.

A good place to go for drop shipping my sister used a few years ago to start her business is worlwidebrands.com they have a ton of drop shippers and good info for starting your online store.