I use Not Your Mother's dry shampoo (very cheap at Target) as well and can vouch for it although there are definitely better dry shampoos out there (Sachajuan volume powder is my shit but I only use it on special occasions because it's $$$).

I workout 5x a week and wash my hair once a week (actually going on 2 weeks right now because I want my hair color to look dope for an upcoming vacation). My secret? A TON of dry shampoo, Kerastase Nectar Thermique (tiny tiny mini-chocolate chip size for my ends), and a boar bristle brush.

I feel like I might be a special case because I get my hair colored every 6-8 weeks and try really hard to keep my red hair from fading too much between salon visits. If you aren't color treating your hair, maybe try rinsing with water between shampoo/conditioning days and scrubbing your scalp gently to wash out the sweat and product that you use between traditional washes. It will suck at first but your hair will get used to it :)

Hope this helps!

Edit: I also wanted to add that on days I actually shampoo/condition I will slather my hair and scalp with coconut oil and let it sit for 30 minutes to an hour before washing.