“No enterprise can exist for itself alone. It ministers to some great need, it performs some great service, not for itself, but for others… or failing therein, it ceases to be profitable and ceases to exist.†– Calvin Coolidge
Then the next step is to figure our what queries your customers would use to look for your business purpose. Put yourself in their shoes. These queries will be really similar to your purpose. They will also go from broad queries – people who aren’t quite sure what they are looking for,  to exact ones – where they have figured out exactly what they are looking for,  and that’s when you need to find the happy medium between relevance and popularity for your keywords.
“The golden rule for every business man is this: “Put yourself in your customer’s place.†– Orison Swett Marden