need weed killer that's safe for my cats to walk in...

Weeds sprout up in my mulch and between the patio pavers, it's overwhelming! I'm afraid to use poison like roundup for fear my cats will become ill from licking their paws after walking thru it. Weeds are taking over my patio and mulched areas! what can I use to get rid of them that is safe for pets? Recently I pulled 3 wheel barrows full of weeds and I just can't keep this up!!!