This is one of those tips that sounds cheap, but I've really enjoyed it.
Instead of lemonade, put a drop of lemon (or lemon concentrate) in water. It's most of the taste, but you aren't drinking a tonne of sugar. I use this to add a bit of flavour to my water in WFH.
Love this, just be careful you're not damaging your teeth with the acidity. I had that issue with kombucha, but if you're just adding a drop of lemon, I guess it's not as damaging!
Edit: Since we are on @frugal, I make my own kombucha!