First off, congratulations for asking for help! This is something that a lot of people are embarrassed by and keep silent on. As you can see, this is a BIG problem. Stress is a HUGE libido killer, as are hormonal disruptions, and then there are psychological issues as well....everything else is on your mind!
Next, sorry that this is a long post. I am going to give you a lot of my thoughts, because I have recently been making this a priority in my own world as well!
Let me reiterate what so many have said, you should begin by talking to your husband and your doctor. You need to find out if there are any medical reasons contributing to this. You also need to identify for yourself and your husband factors that you already know contribute to the problem. You referred to needing time in the evenings to wind down--find a way (with your husbands help) to manage the evenings. Baths are great to relax, but that's not always so sexy and only get you so far.
Here are some other things that haven't been mentioned but might help:
Try and dress in a way that makes you feel sexy. It can be sexy lingerie, a special outfit, jewelry, perfume, whatever works for you. The point is that it makes YOU feel good about yourself, as a woman, a sexual creature. Put it on in the morning and wear it to work (if appropriate). Then, it becomes a part of your whole day. We often need a bit of foreplay to be in the mood, don't always get enough time when at home, so build it into your day. Give yourself the foreplay. Periodically, make yourself think about whatever you are wearing. If there are things that your husband can wear that you find sexy, suggest he wear them from time-to-time. Don't necessarily tell him you think it's sexy--it can be your little secret, and then there aren't strings attached to him wearing it.
If you can get a babysitting coop together with some other couples, it can do wonders.
Another thing (someone talked about reading romance novels), you can write your own little stories (or ask your husband to). It helps to fantasize and imagine. In fact, it's imperative. You must think about sex. Make it a part of your psychological background (quick or not-so-quick thoughts throughout the day).
Think about how you would like to be touched (if at all) then tell your husband what to do. Most men would love to hear from their wives what turns them on, it is a huge turn on for men to know that they are skilled with their partners.
If you don't want to be touched, then restrict him while you touch him. Be fully clothed, and you can touch him when he is undressed or partially dressed. If you love a certain part of his body, trace the lines with your fingertips, or kisses.
Bottom line, get creative. Have fun with it. This is an assignment, you need this to make your marriage fulfilling. But noone ever said homework has to be boring!
Good luck and God bless!