If you want to accomplish anything of value, attach a deadline to it. A deadline starts the clock ticking on your project or plan. It takes your idea and moves it into the realm of reality.
Implementation - putting an idea into action - is hard. It's hard to get started (Newton's law: a body at rest tends to stay at rest...) and it's hard to sustain the momentum. Deadlines can help.
The power of deadlines is pretty obvious. Think back to our years in school and if there hadn't been a due date, I'd still be writing some of my term papers.
But a due date is not enough. There must be multiple due dates at every step. If each project can be boiled down to certain steps, then each step should have a deadline.
Sure, you can re-set the deadline as circumstances change. You might even be able to speed up the process. But an idea with no deadline is like considering going out for dinner and a movie but never deciding when to leave home.
If you want to accomplish more in life, you need deadlines. It's that simple. How about you? How have you used deadlines in your life?