Margaret!
The thread has been pretty quiet lately, but hopefully it will get hopping as people come back from the summer!
Seated jobs are just killers. I know, I have one, too!

I work in a building w/o an elevator, on the 4th floor. I go down twice a day or so, otherwise I'm pretty much seated.
It is really hard to fit in extra time to workout. I have a few strategies, and I use them all depending on what is going on. Sometimes I get up at 5:30 and get on the TM. I will also get on the TM the second I get home, while dh makes dinner. This give me a good hour to workout and shower before the meal, and everyone is happy. The third thing (my least favorite) is to wait until ds is in bed and then get on the TM at 9. One way I'm able to get up early is to go to bed early. If I'm in bed with the lights out at 10:30, I can make it up at 5:30. You will have to experiment and see what your body will let you do. Also, give yourself permission to start small. If you are totally beat after you get home, let yourself have a 20 minute walk. If you are still tired after 20 minutes, stop. If you feel energized, keep going.
Meals and snacks -- I've become a big proponent of fruit and a babybel in the afternoon to get me over that hump. It's a three pt. snack, but leaves you satisfied. The 100 cal packs are dangerous for me. I love carbs a little too much, and I find it hard to stop once I start.
We like to make a menu and shop every weekend, so we know what is coming and can plan accordingly. Tonight we are having stuffed peppers -- we just stuff with brown rice. DH made them last night, all we have to do is bake them tonight. We love to have crock pot meals, those are also a big time saver. Plus with only three of us, we cook once and then freeze the rest for another meal later.
Oh! And it gets better and worse with the growing child. Younger is hard because they require more attention, but older means correcting a ton of homework. DS is in 5th grade, and had 6 subjects last night. I'm hoping that when he's a teen, I'll have plenty of time for me, but
Dona could speak better to that, she's raised happy, healthy young adults!
So glad to see you here, and we can't wait to hear your tips as well!
Maria