discipline
Why take cold showers?
Doing things that might not be entirely pleasant is hard but also the key to self-improvement, and the positive feeling that comes with the success of self-improvement. Challenging yourself with ice cold showers can be very uncomfortable, but it is a great way to build self-discipline and it also has great health benefits.
Eat the frog first!
Having a to-do list and organizing your days into 1-2-hour blocks may help with spending your day efficiently because you will know what needs to be done by when. But there is one more thing to add: Do the thing you are least looking forward to first!