Oishi is getting old and I am learning

Oishi is 4.6 now and her back legs are slower on the stairs in our house in Bang Khae. She used to take them two at a time. Now she waits at the bottom and looks at me like I am supposed to fix it. I can not fix it, but I carry her up the last three steps, which is embarrassing for both of us. Vet said it is not serious yet, maybe early joint issue, and start supplements and keep weight low. I was thinking the Labrador would stay young forever, same as our first lab in Moscow, which lived to 13. She is not that young anymore. We also have Mook the leopard gecko and Tangmo the hedgehog, so the house is full of animals who all need something at different times. Mook is no problem. Tangmo sleeps all day and only wakes at night to run on the wheel. I am now asking my wife to make the couch lower so Oishi can climb up. She says no, the couch stays. We will see.