Idle thought: Did Steve Irwin work out?

Very active lifestyle. He was constantly running, climbing trees, jumping around. Probably played sports too growing up. You can be in great shape without a gym, just hard in the modern world. His job was atypical after all.

I feel as if someone suggested a game of rugby or Australian football, he'd kick arse and be a burden to try and bring down

Yeah, he worked out wrestling gators and being a bad arse. Active people don't have to "work out" because life is their work out. Just keep an eye peeled for sting rays.