If you are like most people in the USA and much of the "developed world", you like to think it is possible to have it all: partner, children, big house, career of your dreams, exotic vacations, good health, etc. Substitute your particular goals as appropriate.
If I had known what it would be like to have it all - I might have been willing to settle for less.
We also like to think this way when it comes to the environment: big house big car, cheap energy, clean environment, there are probably lots of areas where we think we can have it all, but it is complete delusion, and the sooner we admit it, the sooner we can get away from "wanting it all", and on to "wanting what really matters to us". It is important to differentiate between these two concepts, because what really matters are those things we would give up everything else to have.
Pick a few things that you want more than anything else and place them in priority order. Write them down. Continue making the list for as far down as you like. It could even become a sort of "things I want to do or have before I die" list. Plan on keeping this list and reviewing it on a regular basis, it will help you to focus on what you really want out of life.
The problem with wanting it all is that many times our choices are mutually exclusive, or at least mutually exclusive if we implement them the way we envision them. Want to be good at your career and a good parent? The data is pretty consistent, children do better in school and are far less likely to have problems with drugs or the law if there is a parent at home when they leave in the morning and when they return in the afternoon. On the other hand, the people who do best in almost any career field are the ones who are the most dedicated to their work, spending lots of time improving their skills - reading, classes, playing with personal projects and, of course, working long hours. If you follow the conventional path, you can choose one: either be at the top of your field or a good parent, not both.
One way out of this conflict is to choose a job which does not require so much work to reach the peak of your potential skills. Unfortunately, these jobs usually pay far less than more skilled work, so you must accept greater financial limitations on your desire to "have it all". Of course if you have a partner who wants to stay home and take care of the children, that sort of deals with the parenting issue. Unfortunately, you're still not a good parent, they are, however, the children are taken care of. Unfortunately this creates new issues, how good a partner are you? What if your partner wants a career too? What if you split up (you're back to being a bad parent)? Of course there are some ways around this, including hiring someone to help out with the children (if you earn enough) and working from home, assuming you have the temperament and are willing to accept certain career limitations.
So many issues and so far we have only talked about your job, children and a partner. Things become far more complicated and far more likely to fail when you add in a big house, nice car, vacations, etc. Each one of these (and countless other things) which you add to the mix pushes the financial requirements higher, and thereby requires that you do better in your career, regardless of the state of the economy, your health, or how your children and partner are doing. This requirement forces you to spend more time on your skills and/or working longer hours in order to continue to have it all. In the process, your relationships with your children, partner and friends will all suffer. Simply put, you not only still don't have it all, you can't! The harder you try to have everything, the worse things become.
If the above isn't bad enough, it is important to remember that most things we want have to be maintained. It is not enough to achieve/acquire it, you must continue to pursue it each day by maintaining your relationships, your house, your car, your job skills, your professional standing, etc. Some of you will insist that if you have "enough" money, it is still possible, and in some cases you may be right, but a quick review of the high profile divorces and screwed up children of some of the richest people suggests otherwise. In a twisted way, it makes sense that even the wealthiest people fail in their quest to have it all. No matter how rich you are, your imagination can always find desires which are beyond your means.
The only way that it is possible to have everything you want is to want less than can be easily achieved. If you want anything more, you risk losing what you have already achieved. Choose your priorities, do well the few things that matter most, and be happy with whatever you have for everything else.