Good answers above. Also, there is a big emotional component to it. Say a guy is goal oriented, has lots of hobbies, is assertive and so on, but he doesn't really like himself, he is not happy about himself. He doesn't like the way he thinks, talks, how he looks, behaves, what he does for work, how he interacts with girls and so on. It bothers him that he doesn't own a nice car and apartment. Or he may not like something what has happened in the past to him, he hates himself because of that. All this makes him feel that he has low worth, low self esteem...
So basically, you also have to learn how to like yourself enough (I wanted to write love but that just sounds too ugly, LOL). Self worth and self esteem is also a good feelings about yourself, you feel good about who you are regardless what you have or do. You want to convince yourself that what you do is right, and at the same time you'll feel good about it.
Many guys grew up in critical environment. Constant negative words that parents and teachers bombarded us with, such as those below, are after 2 decades quite derogatory, for example:
* Constant Don't do this, don't do that, stop this (Implying that what you are doing is wrong)
* Do better, do your best, improve in this and that area (implying that you are not good enough in whatever you do)
* He is very successful, he's got great job, money, nice looking wife (but you don't, thus logically you must be a loser)
* Money won't make you happy (true, but at the same time it is implying that living in misery, stressing about paying bills, working jobs that you don't like and so fort should somehow make you happy, which is also false)
* You will be happy once you accomplish XYZ (win a race, complete high school and college, get married, get better job, make 100K in one year, ...); This is perhaps the biggest blunt in current society, with this attitude you are always chasing some goals because you live under constant impression that you have to do ABC in order to be happy...
That is very wrong. In reality, when you accomplish ABC, you are perhaps happy for couple of days or weeks - but then you will be seeking something else because you recognize that the ABC didn't really make you happy.
It is a vicious circle, most of people in USA run in this big circle of lies: Make lots of money and you'll be happy. Have a great car, buy a big house, you'll be happy. Spent lots of money, purchase the latest technology and you will be happy. Wait 1 day in line and new iPhone will make you happy. Build bigger muscles and you will be happy. Become a great boss, get a hot GF and open retirement account - and you will be happy. Loose 50 pounds in 30 days and you will be happy. It is all LIES, this will never make you happy. None of it will make you happy, it is only a temporal satisfaction. And if you are not happy, you can't have a real high self worth...
See, once your mind gets into this vicious circle of chasing happiness, you always feel that you are not good enough because whatever you achieve doesn't satisfy you. You are not satisfied, you feel miserable about yourself, so you want to do and achieve more and more...
In reality "feeling happy" is just a feeling, and as such you don't have to accomplish anything. Nothing. You learn to meditate instead. In meditation no accomplishment is needed, no accomplishment is desired. You sit down anywhere and anytime and you meditate, just relax, let go of everything. You sit under the tree and you meditate. You sit home on the floor and meditate. You sit at work and meditate. You sit in the mall and meditate. You accept yourself just the way you are, without money, without great GF, without diplomas or money, without big muscles and nice clothes - and you feel happy. You feel happy regardles with how many girls you slept with. You learn to be happy alone first. That is true happiness.
* So the incorrect formula is: Do ABC, become successful, achieve XYZ --> and as a result you will be happy. For example, get a hot GF and that will make you happy. That is false
* The correct formula is: Learn to be happy first and do what you really like, do ABC --> and that's how you become successful in XYZ. For example, learn to be happy first, then go out and meet girls, and as a result you will become successful with girls. Your happiness will simply attract girls...
Anyone wonder yet why is there so many people on antidepressants, why is there such a high drug abuse and crime in USA? So many fat people? In essence that's the happiness these people are chasing, it is the dream "once I have XYZ I will be happy"...
Observe companies how they behave. First year he makes 40K. Great, but that is not enough. So second year he makes 89K. Also good, but that's not enough either. Third year he makes 500K. Excellent, but the year after he's got to make 1.5 mil. Next year increase profits by 20%. Another year, cut down on X expenditures so more is left for him. Another year save money by firing 10 people. Next year, he changes managers and improve performance by 16.5%; next year cut down benefits for employers so this time he can profit 6mils... He then makes 8 mils, and unfortunately he loses 2 mils in stock, so he goes and kills himself because he can't stand that catastrophe of having only 6 mills... Stories like this are very real, people chase happiness in money, various activities and in girls, and they simply just can never catch it...
See what kind of nonsense is that? I'm not saying that he should be happy with 40K, but why not with 1 mil? Why is there the constant need to keep improving what is already good? 1 mil is way more than anyone needs. It all shows you the constant misery these people live in, constant low self worth...
Also note that the whole self improvement is also a sign of low self esteem. A person feels insufficient, he feels lesser than others, so he starts working hard on himself. After a while he realizes that there is so much to accomplish on self improvement, he just wants to be better and better in everything... The whole self improvement then becomes self masturbation, you feel so great about improving yourself...
So turn the misery around. Learn to be happy first regardless of everything, learn to like yourself and accept yourself just the way you are, with all flaws, inefficiencies, mistakes and falls. Learn to believe that you are already good enough, that you are already a great guy, and that you deserve great things in life such as money and hot girlfriends - should you learn and work enough to get them...
Also learn to treat yourself well anytime you accomplish something. When you see a hot girl, would you buy her expensive lunch because she has a high value in your eyes? Most guys will do it. Well, do it also for yourself, see yourself as a high value guy. Buy expensive lunch for yourself here and there, treat yourself well, appreciate yourself even for little accomplishments that you do... That's how you raise your value over longer period of time...