How many times has someone told you what you should do? Stand up, sit down, get married, stay single, on and on the advice never stops. The shoulds is an endless stream of what other people, or maybe one 'special' person, thinks you should do.
Can't invest your money? Can't decide on a new car?
Just wait for "the shoulds" to arrive. You aren't capable of deciding how to live your life? Not to worry. Someone will be glad to tell you what you should do. But, be careful. Do these people have your best interest at heart, or do they just want to control you? You would do well to think about that. Are they protecting you from their imagined evils? Protecting you from yourself? Well, isn't that nice?
The only thing that you should be doing is what you want to be doing. Write your book, take your trip, get married or don't. Just be prepared to stand the consequences of your decisions. Sure, you’ll make mistakes.
Everything you do will be not be for the best, nor will all things be bad. Few situations in life are "once in a lifetime," and what if they are?
In life one must learn. So learn.
No one gets through without making mistakes, and it's a good thing too, for nothing is more valuable than your mistakes. You learn from them. And those lessons will not be soon forgotten.
Live your life. Your life, not the life other people think you should. Someday you will be too entangled, to indebted, or just plain to unable to do what you should have done. And then, my friend, it will be too late.