Complementary workouts to climbing

Hello, I just got back into climbing and I'm looking for something to do on some of the days I'm not climbing.

I climb four days/week right now. But I want to go down to three climbing days, two complete rest days and two days where I do something else.

I just don't know what that 'something else' is. I want something that trains different muscles than climbing, so I don't injure myself...

Any ideas/recommendations?

Thanks a lot:)

PS: I just want to do something good for my health. It's not strictly about weight loss or muscle gain. But I also don't strive to have a perfect climbing body. I'm really open to anything, even if it's just running or so...