Stressed wife
There isn't much I love more then exploring my wife's body and giving her pleasure. She just isn't into it. Rarely wants sex. She could go months without it. Used to be I could get her turned on and enjoying herself but that seems to have faded as well. Now, she will let sex happen but she doesn't participate and just waits for me to get it over with. We had a baby six months ago, she is an MD, and just finished her residency. She is studying for boards and we are moving. So she obviously has a lot going on. I wish she could see sex as a stress reliever and vital for our relationship. We have talked about it, hasn't helped. Thanks!

Jarow, it is wonderful to know that you love to pleasure your wife. Perhaps I can give you some insight as to what she is experiencing. It is difficult to see sex as a stress reliever when she is so overwhelmed. Pregnancy can take a huge toll on our bodies; pain, decreased lubrication, exhaustion, etc. All of which complicate sex and sexual desires - even months later. Perhaps you can help her de-stress in non-sexual ways, first. When she can disconnect from some of that, her desire may come back. Ask her what you can do to help her feel less overwhelmed. Hopefully this will recharge her...and you.
Anxiety, stress, and depression are desire KILLERS. 80% of women who are depressed and 90% of women who are anxious experience a drop in their sexual interest. When women are stressed, more of than not sex drops right to the bottom of the priority list.
So asking her to think of sex as stress relief is like asking a her to think of her commute as an opportunity to learn a new language on audio book - it might be, if she were in an entirely different from of mind, but right now she just isn't interested.
What CAN be stress relief is non-sexual physical intimacy, as Logan says. Cuddling, hugging, kissing, not as a precursor to sex, but for itself, is a stupendously effect stress reliever, especially for women.
It could backfire, of course, if she ends up feeling pressured for sex.
But gradually it'll help to reconnect her with her body and with you. Give it time.
You are very sweet for caring so much about your wife's enjoyment. I have been on that side of things, however, and really it had nothing to do with my husband's ability to get me turned on. I needed to find my way back to my sexuality myself; new motherhood, with all the hormones, exhaustion and identity confusion really through me for a loop. So maybe instead of thinking what you can do to give her pleasure, think of what you can do to help HER find her own pleasure (in bed and life) again. Clear her plate as much as you can, encourage her to find things she loves and do them, showcase your competence with the baby and I'd say give up the pity sex for a while. A turning point for us was when my husband went on a sex strike. He would cuddle and touch, but he announced that he was done having sex with me unless I authentically initiated it! The surprise was that with the pressure off, I was able to see glimmers of desire in me, which we were able to gently coax into real want.