Now this topic has changed a bit over the years. The way it used to be done, if you look at the history of Google and how it ranked pages, is much different then it is today. If you sold pencils back when Google first came out your biggest challenge was finding out where you could possibly spam the word 'pencils' on your website without it looking like total garbage. Aw yes, the good ole days of having a white background with white text on the background that just said 'pencils' five thousand times! Those were the days!
However, Google does indeed smite those who now conduct themselves that way. So don't do it. You'll get noticed, but probably not the way you're probably trying to be.
You need to choose your keyword theme. When you choose your keyword theme you are not just choosing "fitness" you want to choose something more targeted such as, "fitness for athlete" and even that could be seen as too broad. The more targeted your keywords or the exact purpose of your page the easier it's not only going to be to rank for keywords but you will also be able to start ranking for long tail keywords, and those are much easier to rank for since they are so specific. An example of a long tail keyword would be "spicy chicken soup for vegans." When you you start getting long tail keywords you will begin to find gems that you will easily rank highly for that you weren't even aware of.
This post is in the works. Bookmark and come back soon..
Meanwhile...look at some of the other articles.