Some successful community professionals express surprise that community building is such hard work.
They launched their communities and it just took off.
Yes, this really happens. Communities can go from inception to maturity in a matter of weeks. Facebook was like this (back when it was just a community for students at ivy league universities). You don't hear many stories about Facebook actively promoting or recruiting people at different colleges. In fact, for the first 2 years the site was closed to most people.
They built it and people came. Everything just fell into place. It was exactly what people wanted at the exact time they wanted it.
This happens when you get the concept right. The stronger the community concept, the easier everything else becomes.
Don't rush the conceptualization stage. Spend at least a month on this (maybe 3 months). If you get the concept wrong everything becomes far harder. Research is boring, but vital. The more data you have, the more closely you can create a concept that matches what people want, the more successful your community will be.
This doesn't mean you will have less work. It does mean your work becomes far easier.
Almost everything organization that fails, skips this stage. They assume they know without ever talking to a representative group of their audience.
If you do this badly, everything else (getting people to join, participate, invite others) is much harder. If do this really badly, you've killed your community before you begin.
Take the time to do it right.