Teaching kids about money is challenging, but the lessons are invaluable.

So rather than stress about explaining why your son can’t have a toy, or why your daughter has to put the cookies back on the shelf, take advantage of those opportunities to teach.

I’ve never forgotten what my grandmother and mother taught me about saving. Since it’s Mother’s Day, the lessons are fresh in my mind.

Read: Thanks, mom, for teaching me about money

My younger brother Max and I visited my grandmother often as kids, and she was a tough woman. Though she sometimes spoiled us, she taught us lessons every visit.

When it came to money, she was strict. My grandfather died when my dad—the second youngest of five kids—was only 11, and she had to provide for her family.

She wanted to teach us about budgeting, so she told my brother and I to pretend we were visiting a grocery store. She gave us each $50 in Monopoly money and told us to buy items from her walk-in pantry.

Max and I each filled a shopping bag to the brim and went to the teller (my grandmother). She priced each item and told us how much we owed. Since we only had a set amount, we had to decide what to keep.

We were competitive siblings, so I always made sure I had the most money left over. I learned to work with the money I had, rather than overspending.

Read: Why financial literacy matters

My mom taught me another lesson. When I was 10, I found $100 at a convenience store—it was the best day of my young life.

Rather than let me walk off with the cash, though, my mom took me to the bank to check if it was real. She then had me phone the store and wait a month to see if someone came for the money since it was a substantial amount for someone to lose.

It was a long month. But even though I pleaded to have it, she stuck to her guns. After no one claimed the $100, she helped me decide what to buy with it. Though I could have burned it all on teen magazines, she suggested I put it toward the GT Snow Racer I’d really wanted.

Read: Kids more financially savvy than we think

These are two of my best memories.

Your kids may not thank you now, but there will come a day when they realize how much you’ve helped them. (They may even put you up in their future mansions. That’s my Dad’s hope at least.)