Welcome to the forum Brownshort.
There’s a good reason why this topic “has been done to death”, it’s very common and for the partner in the marriage who’s feeling the way you do, it can make for a very sad and lonely life. Not to mention the negative effect it can have on your self esteem and confidence.
No doubt you’ve read the usual suggestions like do more house work, gifts and surprises, compliments, be well groomed and get yourself in shape. While all these things are great to do, if they are just done in isolation, I find they rarely help.
I’m also going to assume your wife is not suffering any physical problems which would make physical intimacy problematical. After 30 years I’m also assuming your wife is post menopausal and low libido is common in this cohort. If that is the case, it’s unreasonable to expect her to perform if the basic drive is not there. However, that doesn’t excuse her from displaying affection, kindness and a shared intimacy (not necessarily penetrative sex). You also owe her the same consideration.
There’s really only two outcomes and you have to think carefully about what you want and what you won’t accept. The first outcome is that nothing changes and the second outcome is that there is an improvement that shows there is life left in the marriage. The improvement maybe is less than you were hoping but anything should be seen as positive.
Obviously, you have brought the subject up with your wife and she has indicated that she doesn’t see a problem and therefore there’s no need to change, Now this is where you have to be really clear on your end game. You need to explain to her that you are sad, lonely in your role as a convenient house labourer who also works full time outside the house. It is not your idea of a happy and fulfilling marriage. Because you feel the way you do, how can you be expected to live this life with no prospect of anything changing and yet appear a balanced and supportive husband.
If she truly loved you, she would make some effort to make you feel special (after 30 years, swinging off the chandeliers is off the agenda), just simple signs of affection and the odd compliment satisfies most blokes your age. If she won’t budge and meet you at least halfway, would you be prepared to risk the end of your marriage? Because in a lot of cases I’ve seen like yours, that is what it may take.