"Pursue that business which you are great at and love doing, provided by your ideal buyers. It’s as simple as that."
That's a nice, neat sentence and it sounds easy, but it takes a lot of time and experience to get to that level of professional easy and grace.
More often than not, we don't know what we don't want until we have it. And then we learn. The light bulb goes off in our minds and we suddenly get it - "Oh, I see. I don't have to work with people who constantly frustrate me!"
It's a revelation of maturity and wisdom, but it can happen at any age, and not by mistake.
First, we have an "Ideal Clients Only" policy, and then we treat each other as ideal. That's a feature of my personal branding. Feel free to choose it for yourself, too!