After a long break, I finally got back to kettlebells in May.
Last summer my knees were chronically sore. I stopped all strength and cardio work and waited for them to heal. It took over nine months for me to feel comfortable enough to begin doing a few swings.
I've slowly eased back into swings and get-ups, but not every day. I've also learned that stretching my calves and hamstrings (and everything else) is really important for my knees. The ligaments and tendons in my knees, ankles, and feet are very tight from several years of martial arts (and even more years of being alive), and stretching makes my lower limbs almost pain-free most of the time. Stretching also helps keep my plantar fasciitis at bay.
The only difficulty I have is kneeling during a getup. I'm experimenting with ways to get around that, but for the near time I try not to do getups on consecutive days.
Nice to be back doing swings and getups. I've missed them.