If you say "I'm bad at maths" or "I hate maths," your kid internalises that maths is something to fear. They literally learn anxiety from you.
This doesn't mean pretending to love maths. It means talking differently: "Maths isn't my strongest subject, but I think it's worth learning" or "I struggled with maths, but your brain might work with numbers differently than mine."
Your vulnerability + confidence that your kid can do it = the balance they need.