Having seen data that most have not (believe me or don't, but if you want to take a chance on a random anon user I would say I can give a more data-informed take on this exact issue than 99.9% of people), it's really not as dramatic of an effect as lonely people would like to pretend, but even subtle as it is numerically, it does affect the feeling. An extra cup of water still feels like a world of difference if you're in a desert.