I make it my business not to sweat the details on a daily basis. If I'm spending money, then I spend money. I will not collect coupons as I feel it is a waste of my mental energies and time. If one comes upon my path I will consider it.
I also consider whenever I'm buying something whether it's necessary, or worth having at all.
These balance out to a nice frugal lifetstyle. Nowhere near ERE/MMM level, but good enough for me. Further improvements upon my lifestyle provide only marginal returns in savings rate, vs. a little bit too much of a hit for myself in terms of quality of life/enjoyment.
And changes in the near future in my life will completely distort the meaning of these words, "cheap" and "frugal".
Edit: That said, wtf does your mom mean by "mean"? Corporations don't have any right to my money, **** them, if they provide a sale below cost then I'll take them to the cleaners if I have use for what I get.