Somehow I'm not connecting protein with Gatorade. That's like putting ground coffee in orange juice to me; protein powder is best left to shakes and smoothies.
In all seriousness, I think the Gatorade with protein idea is a great example as to what you should do, that is, if you're not all that ambitious to create something. Any slight improvement on something that works well now which can in turn make it better and create value is the way to go. If someone created it before you, no problem. Just pick/create something that sounds relatively new to most people.
More importantly, do you know you can build it and if not, do you know anyone that can? I once took an entrepreneurship course, where I wound up creating a neural network-based software bot, which was more computer science than business; needless to say, it took me all semester to build the darn prototype. It wasn't just me as I actually hired some help and got it done that way. In the end, I was just glad my GPA didn't go up in flames.