I believe it’s things that benefit you’re physical health(body) so like going on a run
Using half normal saline or hypotonic solution is appropriate in patients who are dehydrated. Hypotonic solutions have less osmotic pressure making it absorbable attracting more water thus it makes intracellular volume of cells increased, which leads to patient's safe hydration.
I can boost my motivation by changing my sleep habits and taking a walk everyday after school and I will try to do something positive so that I have motivation to do my homework
Depends on what you mean by cold.
If you mean like cold, like tempurature, then wear the smallest amount of cloths, and use air conditioning.