Catnip causes a harmless euphoric state in cats that lasts up to 15 minutes, 

sprinkle some on their favourite cushion or toy

Feed some to you cat 2 or 3 times a week or add to toys

The natural constituent of catnip is nepetalactone,
 which is what makes most cats respond to catnip. 
However, not all cats respond, why not give our trial size catnip a go if you are not sure!

Our own Cat Yuki (Burmese) used to ignore the cheap Chinese Catnip  but goes nuts for this stuff

now this New strain of Catnip she goes totally screwy