Can anyone suggest some basic things I can do to help me cope better with the physical demands of pregnancy?
I'm not quite half-way there, BE"H, and I'm totally exhausted and finding the pregnancy to be harder on me physically. The little things are harder to cope with. I think it's a combination of age and the demands of having 4 kids, one of whom is an active toddler who is home full time.
So, remind me of the little things I can do to support my body while it works so hard (besides more sleep, which I'm getting as much of as I can).

Herbs, herbs, herbs...

dandylion, nettles, alfalfa...blackstrap molasses...floradix iron+herbs

That should get you started on your search. Please DO make certain that these are appropriate for YOU, before you take them.

are you experiencing any specific symptoms?

Exhaustion, digestive slowness, sore muscles where my belly is expanding, and the perenial varicose veins that I need to find a decent pair of support stockings for.
B"H the nausea seems to be basically over. I am not getting it every day any more!
Mostly, though, it's feeling tired and achy and old! I can't keep up with what I need to get done. Not just not finishing the dishes, but not getting more than a couple done before I'm tired and start bumping the dishes on the faucet. I can't do a big grocery shop and other errands in the same day without feeling like I overdid it. Mommy brain is making it hard for me to make important phone calls.
I wondered about my iron levels, but they were good when tested. My midwife wasn't concerned that my symptoms are out of the range of normal, but with a family to keep up with, I would like to function better!

Julriv - molasses is interesting - I've been craving black licorice.

i rec. liver once a week and magnesium supps. magnesium should at least get rid of achy and clumsy. i can only vouch for the effectiveness of natural calm.

I agree with JulRiv. With each subsequent pregnancy I have felt my body needing more and more supplementation. Never in my life have I been low iron or even close until my last pregnancy when I found myself craving sand of all things. I think with each pregnancy we have to work harder to replenish our body's stores of vitamins and minerals.

Interesting.
I guess I need to be more careful about getting the best nutrition I can, and daven that the toddler starts sleeping better. I think the two combined should go a long way to helping me feel better.

Update:

I'm starting to feel somewhat human again! And I can't say that I've had a chance to do much about the suggestions you've given, besides trying to eat more decent protein and iron and dealing with the constipation more aggressively.

I guess part of it was just a stage of pregnancy. Looking forward to the other ideas helping, too, because I'm getting that pre-Pesach urge to tidy, and I'd like to take advantage of it!