overbearing nanny?

Im a nanny of two boys 2 and 3 and i bring my 6 month old baby girl with me. I want to be fun but i feel like im coming off to "mean" ehen im just lookingout for their saftey. Like today at the pool i kept having to tell them to stop running and chasing eachother in the pool or wed leave. I just didnt want anyone getting hurt or swallowing to much water cuz of dry drowning. So we left early cuz i was tired if having ti tell them to stop doing stuff that could harm them. Do u think im being to worry wartish? Lol or am i in the ok?