I would like to expound on this a little:
'Does this mean its all on you to have a happy sex life? Yes and no.'...
Its really up to you wither or not you have a happy sex life. The key to sexual happiness lies primarily within your psyche and your views of sex, yourself, and your spouse. If you have preconceived notions about sex, your body, or your spouse that contradict what you think you're supposed to feel then that makes it difficult for you to relax and enjoy it. If you think your body is ugly, or you refuse to believe that your husband loves you, or you think sex is somehow dirty, then it doesn't matter what your husband does, you're not going to enjoy what he's doing and every attempt on his part is going to come across as selfish and an invasion that can leave you feeling violated. If this is the case with you then it may be necessary to seek the help of a therapist to help you understand why you feel this way, and to address it. This actually was something I had to do. I had some unfortunate experiences in my life that made me feel that ALL men were selfish. I felt sexual attention, even from John, was motivated simply by the desire for sex and any woman would do. I felt he only targeted me simply because I was there.
When I got married I had no idea that this was how I felt. All I knew was that I was starting to hate sex. So I had to overcome those misconceptions, have a number of open and honest conversations with John to even begin to have a chance at enjoying spending intimate time with my husband. Though I still struggle with it at times, after taking steps to move past those feelings I am much more able to relax. If your spouse has similar issues then it would be advisable to encourage them to talk about it, either with you or with a trusted friend or therapist.
If this is not an issue for you and you feel perfectly comfortable with sex but you just don't like it that much, well, you have to figure out why. Once you do, you should have a kind and honest discussion with your spouse about what your sexual needs and desires are. Usually if you start to not like sex, when you have never had a problem with it before, its probably because one or more of your needs are not being met, and while its your husbands job to try to meet these it is YOUR job to make sure he is aware of it. You cant get mad at your husband for not doing something you didn't ask him to do.
Also, don't be boring. Be generous and adventurous to the best of your ability. Obviously, both of you need to be comfortable with any new things you try, but sometimes you may actually end up finding something you really like by being willing to try something you might not have otherwise. As for the generous aspect...not to be too blunt but if you want your husband to give you oral but you refuse to give him a blow job then you cant expect him to get too excited about returning the favor. You can never expect your spouse to do something for you that you are unwilling to do for them, and vice versa.
Having a good, even a great, sex life takes two. The biggest issue most women face is that they don't want sex that much because when they do go through with it the sex is not satisfying. This does not mean that they dont enjoy it. You can like the sex without being totally satisfied by it. Satisfaction in this case refers to a feeling of fullness or completeness in emotional and/or physical gratification. This means that if your husband approaches you and says 'Hey, wanna f**k?' and then expects you to hop to it and make things happen...but what you really wanted was for him to give you a hug, look into your eyes, tell you he loves you, then kiss you till you melt... well, his invitation to get busy is going to be very distasteful to you. This is where your husband has a responsibility to make his proposal for sex appealing. Its fine for him to say 'Wanna f**k?' every once in a while, I mean, who doesn't enjoy a quickie now and again?! But if that is how he tries to initiate things on a regular basis its a wonder you ever get up enough desire to have sex with him at all! Unless you like that sort of thing. Its just like the section I wrote on apologies. You both have to learn what makes sense to the other person, you have to learn each other's language.
Men view sex as an act of love, as where women need love to have sex. Another way of looking at it is that when a man wants to express love for his wife he seeks to have sex with her as a physical manifestation of that love, but when a woman wants to express love to her husband she does things to try to make his life easier like make sure the house is clean or that dinner is ready when he gets home, but most of all a woman will use physical but not overtly sexual physical acts such as a long hug, a meaningful look and a kiss before telling him she loves him. Women need those sorts of acts to be reciprocated in order to feel that her man loves her too. Why? Because that's what makes sense to her. What a person gives the most of is what makes the most sense to them. Husbands, if you notice that your wife gives you a hug and a kiss every day when you first walk in the door, guess what? You can bet that loving, non-sexual physical contact is important to her. SO to make an appeal for sex more appetizing, and even exciting for her you might try surprising her with a hug, a tender make-out, and then let HER decide if its going to lead to sex. Chances are if you don't pressure her she will end up asking you if you want to finish things in the bedroom. So men need to, wither or not they understand or agree with it, try to do things their wife finds enjoyable, and if they dont know what that is, well, they need to ask.
I hope this cleared up some things and made some sense :) Good luck and have fun! I mean it! Go...!