Overweight and scared about pt

I'm 360 pounds and 6'3. I enjoy weight lifting but running is really hard on my body. I'm scared that this will be too hard on my body. I've done some really intense physical things in my life but I'm just scared that I will be pushed too hard and kicked out or make it harder on my group like on hikes and that sort of thing. I'm leaving tomorrow and the stress of this is pretty intense. Again I really want to do this but I've seen some pretty intense descriptions as to what training looks like.