I give my cat Cosequin and it is great.
The vet recommended it about a year ago after I told her about my cat's recent reluctance to jump up. She would get ready to jump to a table or something, and assume the jumping position, but hesitate.
Ever since she has been on the cosequin supplement she is much more youthful in behavior. It's great!
It comes in capsules, which you can sprinkle on the food. I feed dry food, so I put some water in the capsule then sprinkle it on the food so it sticks. If you use wet food, you won't have to wet it first.
I give 2 capsules a day, one each, when I feed in the morning and night.