Help? High school? Getting to classes?

I have 7 periods a day and lunch and interval. The school where I go to is large. Some times I have to run from south-east to north (which is pretty long because the school is in a rectangle shape, coincidently it’s longer in north and south) I literally have to run or i’ll End up late. My shoes are new so they’re pretty uncomftable, I have converse leather high ones so it’s a bit painful when I walk or run... then I have to run a long distance... someone help me. Oh yeah I forgot to mention my super heavy bag with all my textbooks, laptop and super heavy drink bottle in the middle of summer. There aren’t much drinking fountains around the school anyways -.- help?