Nancy Regan got it right, even though we all laughed at her seeming simplicity. Those two letters are always the safest, easiest way to go. Just saying "no" will keep you out of a world of trouble. Although it can be extremely difficult, at some point you do just have to say no. I will no longer do... fill in the blank. Of course it is a bit more complex - there are many things that drive behavior. Our pasts, our character and happenstance all influence our decision-making process. Most of us have learned right from wrong, no matter how subjective, and know when we should say no, even if we don't say no.
Some would argue "yes" is far easier. Just agree and go along, get on with it. Say yes to that thing that may or may not be good for you. Get 'er done as the cable guy says. It seems more risky though. You're agreeing to action versus inaction. No almost always means choice "D", none of the above. No always mean no.
And sometimes yes means no and no means yes. Yes to no more drinking and no I will do that. Kind of like positive and negative reinforcement. They both end up getting the same place but just take a different route.
Decisions are always hard, there is no doubt about it. But always saying yes, or always saying no is never going to get you where you need to be. We all know many nay-sayers and yes-men. I think we can easily identify the Eeyore or brown nose. I think they are universally disliked.
Indecision, self-doubt and fear of failure clouds our thinking. Sometimes we are so afraid of failing that we fail to decide and then we surely fail. All we can do is to make the best decision based on the information we have, right or wrong. And sometime it will be either or both. Deliberation is critical process that needs to cloud our mind. It's OK to be unsure but resolution requires action, positive or negative. If you choose to not to choose, as Rush said in Freewill, you still have made a choice.
So yes or no isn't the right answer. It's about taking the best action that may be right for you, unafraid and accepting that in-spite of your best efforts, you may be wrong. But you may be right too.
We live in a world of imperfect choices. Somethings may never be completely right or wrong. Decide to decide and move forward. If you take the world as it comes, hopefully you'll get it more right than wrong.
Say yes to no and no to yes and one of them is bound to be right, no? Just do it!