Sometimes we are so afraid of missing out on opportunities that we say yes to everything that comes along, without really considering the dynamics of the situation or its implications.
You're talking with a colleague; He proposes some type of business deal and without really thinking about it you say YES because you're afraid of rejecting them by saying NO. (And of course you want the business). You're a smart person - there's nothing you can't do and you know that you'll get the job done, no matter what.
Several months later you realize that the whole situation is ridiculous... You think back and realize that the goals were never realistic, you didn't scope the project or charge enough to do the work correctly, and the project didn't even align with your overarching personal and/or business objectives.
It's all crumbling down now, and both parties know that it's time to call it quits. You both feel terrible because there is disappointment in your performance and a sense of waste, both in terms of time and money.
This has been me several times in my career. It's important to realize that, sometimes, "NO" is the correct answer. In fact, "NO" should always be your first answer (I read a book many years ago called "Start with No" by Jim Camp).
Only after really thinking the project through and having 100% confidence, based on research and correctly scoping the project, should you say YES. You must be sure that the project is homogeneous with your long term objectives (in business and life).
Just a tidbit of random experiential advice on this boring Sunday afternoon.
Happy Memorial Day!