well its hard to run when you are a beginner but with time you can get better.
i remember my first day at self-defence, my trainor make me run for 2h and do a fking 300 push ups 30 per time and a shit ton of ther exersices that i never heard about
2 hours later i couldn't get up from my bed without grabbing my knees lol, now its just normal
just keep practicing and dont be a lazy ass like uppkicker