I own two of these. It took me a while to figure out ice with the infuzer tube.
If you’ve never owned one of these before I’d buy a small “BB” ice tray for your ice. Put the fruit in the center tube after cutting it up (I love lemon) then place the tube halfway into the bottle then start adding the ice cubes and you slip the tube farther in and seal the bottle.
I really like these I just wish they were bigger but having to move around to go back and get more water does keep me active. I used to use these at work but I am always on deadlines so I am just using these at home or in the car sometimes bring them to work if it’s a short day. If you don’t care about having lemon/lime/ext floating around in your water you can skip these and keep doing what you’ve been doing with your water-fruit combo.