Stay at Home Moms (and Dads)...what do you do?

Work out outside or at the gym since you can leave...

Since your husband is sleeping during the days you could get in a pilates workout. That is gentle and quiet and good for working on your core. There are lots of pilates videos on Youtube.

I have a 5 year old son who goes to school in the afternoons so I do exercise videos in the afternoons after I drop him off and run whatever errands i have planned for that day. A couple of mornings a week I do a figure skating class and luckily where I do that they have childcare so he goes to the kids club and has fun while I get in a workout on the ice.

Hope you can figure out a routine. I find until you find that routine it is so easy to just sit at home doing nothing.

Work out outside or at the gym since you can leave...

This. There isn't much more to say. You post is confusing.

Stay at home with a gradeschooler, wanting to set a good example and lose weight.

Do your long slow cardio during the morning, right after school starts.
Make certain you have a healthy eating plan in place for the afternoon/evening, and document it well enough that your kid can see why you planned it the way you did.
Find two fun exercises, and a cool science experiment video for the evening. Try to understand the science behind it well enough you can do it with your daughter if she gets excited about it after you watch it with her in the evening (video is sometimes a good reward for finishing homework). Make certain that homework has appropriately timed active breaks (like those fun exercises you found).
If there is a subject that she is having problems with, try to find new ways of learning/teaching/practicing it, since her problem is probably not the subject, but the way it is being taught.
Garden: good food, decent exercise, and an awesome example of what self-reliance meant.
Have a regular volunteering schedule: keeps you from "no adult conversation" insanity, helps the community, and gives you a better network for solving the problems that you will be confronted with as your child ages.
Make something: paintings, a video game, furniture, costumes, insane dinners, a radio, a dune buggy, a novel, an airplane: the more outrageous, the more you will learn, and better you will demonstrate that a human should not be limited by their goals.
Find a subject that you like, and take on online course (there's a bunch of free ones) to get better at it, and do homework "with" your daughter - bonding and good example all at once. Maybe take up public speaking, or storytelling (what kid wouldn't enjoy a parent telling stories awesomely?) - by doing this through Toastmasters, you get another chance at connecting with other adults, as well as great feedback.
Learn a new dance, a foreign language, an ancient language, nuclear physics.
Memorize a play: a classic, or just your favorite.

Is that enough ideas?

TL/DR: Live the example you want to be.

I actually do understand where you are coming from Op. It's really hard to motivate yourself to do anything when there are no consequences for not doing it. No kids to need stuff. I have two semesters before grad school so I'm at home with the dogs and myself while the hubby is working. What helped me is making a to do list in the morning and sticking to it. The hubby is so happy when I'm productive, not only do I get stuff done, but I feel better about my situation!

Work out outside or at the gym since you can leave...

This. There isn't much more to say. You post is confusing.

I don't think it's confusing. I lost my motivation when I left my job. It was part of my routine while I was working...now I find it difficult to get into a routine when my days run together. Yes, I can leave the house, but I don't...

So then you're looking for motivation, not ideas?

My days vary. Fpr a while, after my kids were all in full time school, which was just recently, since i had been cyber schooling my son who is 13 and has autism until August 19th of this year. After that, I sort of went on a daily shopping bender.

Every day I would shop. I bought all kinds of stuff. Then I got sick and since then I have been trying to not medicate with shopping, either online or in person.

I have painted my baseboards this year, since the kids went to school. I usually do a the laundry twice a week, I batch it, rather than doing a bit each day, that way I fold more at one time but get it over all at once.

I try to get my floors cleaned every day with the vacuum. I have old wood floors and an old golden retriever and kids who drop stuff, so I try to keep that mess cleaned up once a day.

I keep the dishes cleaned, that's harder since our dishwasher has been broken since June 28th. So I handwash. I try to keep the sink empty and clean. Our kitchen is 8x10, so there is no room for mess, I literally HAVE to keep up on this, although I hate cleaning with a passion.

And, since i have been sick, I take a nap before the kids get home so that I can deal with homework and their attitudes (ages 9, 13 and 15).

So that's pretty much my day. I also take the dog out to pee, poop and I deal with the mail, the bills, etc.

I wish I could say my house was spotless, but it's not. But it sure is better than it was when the kids were all out for the summer. At least now if a neighbor comes by, which is often, I am ok with it and not cringing and wishing they would leave.

I have been out of the workplace for 15 years, except for a stint at my son's school as the cafeteria janitor two hours a day, five days a week. It was horribly, demeaning work, because the people at the church school were mean to me and acted like all I was was a janitor. They even addressed me as "The Janitor". I like working at home much better.