When I feel down with my progress the thing keeps me going is the "feel" of water, experimenting with water reactionto pressures, working on proprioception in the water. Swimming in another person turbulences (and make it into a smooth ride), etc.
Putting the chronometers down 10 minutes (or more) and rediscovering "water", keep the experience fresh, an on going discovery of the medium which we are travelling through: time... I mean water :=)
Think we all
should have that in mind (at least down on the floor of our "Mind-Toolbox"), when going for swim.