I used to save my gift cards for something special; some of them went unused for years. But then they introduced inactivity fees. They didn't generally announce it, but I found cards where I'd lost like $40 value in bullshit fees. (I mean, really, it doesn't cost them anything in operating costs to keep the gift card in the computer; this is just bullshit "we didn't think you'll miss it and we'd prefer not to have this liability on the books, plus we'd really like your money without having to give you inventory".)
Nowadays when I get a card, I go and spend it almost immediately and excitedly tell the person about whatever I bought. In reality, I also stick the equivalent amount of cash into the envelope and put it aside. When there's something I can't quite justify buying, or I need a little pick-me-up, I open the card again, re-read it, and buy myself a little treat.
And when I get a little extra money in the budget, I replace the money and put it with the rest of the cards.