First I would say in regards to nihilism, my view of the term "meaningless" is that it is fairly confusing and I need to clarify some things before answering that question. The whole "life is meaningless" statement only really makes sense when talking to someone who has some kind of altruistic or religious view of why humans have been put on Earth and what they should be doing, perhaps also those who believe in fate or destiny etc hopefully you get the idea. I don't want to get too into the word "meaning" as in philosophy it can be really confusing and I am still grappling with all the different kinds of meaning that exist. Now you say I might be an existential nihilist, I will look into that but for now I will call it just nihilism. But to digress, I would prefer to say that I am, within the context of nihilism, against the pursuit of moral and spiritual outcomes, or outcomes of principle.
Values are just preferences, substantiated by more values in what can often amount to a never ending loops or an admission of preference but never being able to link the "goodness" of a concept with evidence based in the physical world. I would be happy to demonstrate this but for now I will continue under the assumption you accept that fact. Moving forward, any action which is aimed at conforming with, aspiring towards, sustaining or leading to the establishment of a value amounts to complying with an artificial demand or requirements which may or may not provide you with emotional or social rewards. To give an idea of what I am talking about, I am talking about values like chastity, honour, obligation, masculinity/femininity, ethics, purity, innocence, prestige, respect, rationality, truth, competence, good/evil and image. This isn't an attempt to describe all of them as that would be impossible but the common theme is that these values require things from us and shape our perspectives of ourselves and the world without being a part of the world itself.
When I speak of things like competence, for example, one could be down about their inability to attract the opposite sex, match their standards or defeat an opponent and to simplify these desires as being caused by values may be an oversimplification but I hope you get the idea as I am not sure how to explain this further without an ever larger wall of text. As I said previously, nihilism is a rejection that genuine meaning can be attained through the pursuit, or living your life in accordance with, these kinds of artificial concepts.
I think that values can be beneficial psychologically, functionally and organisationally but they can also be very harmful and redundant to us. Nihilism is not a goal, a nihilist only has to reject the pursuit of moral and spiritual outcomes, or outcomes of principle. A nihilist can eat what he wants to eat, say what he wants to say and think what he wants to think and all he must do is reject that pursuit and nothing more. Nihilism is not a resentment or rejection of psychological needs or desires, distinguishable from values through their casual relationship with the physical world. I don't know if one can dismiss psychological needs but I think every healthy person has them and that values are necessary to satisfy some of them. Some psychological desires might be a desire to achieve, for sexual intimacy, self-esteem and needs; the ability to comprehend the social world and their ability to elevate themselves within it, to feel that they possesses things of worth and that they are of worth. Values exist for such purposes in my mind or at least they have the consequence of being very significant for our psychological needs and desires.
However values are not tailored for us, people understand them and accept them even when they are harmful to us. Their usefulness can depend entirely upon your position in them, there are countless examples of this but let's look at obligation as an example. If you look at an obligation that a son might feel to his father, this is may provide the son with meaning but this sense of obligation probably involves doing things which would otherwise be undesirable for him to do, certainly if you believe strongly in that obligation then you might be compelled by it to act in ways which cause you distress and pain. From the perspective of the father, he can invoke this principle of obligation and convince you to do things that you may have otherwise refused to do and there are many benefits for him.
If you derive pleasure and a sense of achievement by devoting yourself to your father out of a sense of obligation and you evaluate the social, emotional and psychological pros and cons and decide it is a good thing for you; choosing not to because you reject outcomes of principle would be an inherently non-nihilistic thing to do as refusing to do something for that reason would amount to an action based on achieving a principle. Equally if you believe your life has meaning and that makes you feel important and happy, yet it required nothing of you that you were disadvantaged by giving then it no longer becomes a pursuit of a spiritual outcome but rather a direct approach at acquiring contentment and a "healthy ego". It is meaningless to pursue happiness but one does not require that kind of motivation, meaning may contribute to that pursuit but it is not a requirement and ultimately I believe it is an inefficient way of approaching the issue. I think that what meaning offers the ego is self-esteem, importance, purpose and achievement but often it comes with a hefty price tag. I don't think it is always bad and it can be effective but I won't get into why it can't be the most effective method because that is another wall of text in itself.
"The efficient way" is to view values by their pros and cons, be flexible in your belief in them, your application of them and the methods you use to satisfy your beliefs. Some examples of this might be changing your beauty standards to suit how you look, or viewing intelligence as less important if you yourself are unintelligent. Have your values work for you rather than against you and pragmatically pursue only psychological, social and emotional benefits. This may mean that you cannot simply disavow any value which is disadvantageous to you and it won't solve all your problems but I do believe it is the most efficient and direct way.