What did you struggle with when you started swimming?

Basically, what did you struggle with when you started swimming and how old were you? I kind of want to see if others have had the same troubles as I. I just started swimming recreational this year. I am 20 and started due to my knees starting to bother me more by running, which I usually do. There are a few things I can't seem to get the hang of: 1.) I can't last very long in freestyle. I can only do 75 at most before I have to stop. I think this is due to my breathing pattern. 2.) My kick is pretty weak, when I use a kick board I don't go fast at all. Due to being a runner before I guess this is a common problem. 3.) I'm trying to get the hang of flip turns but my push off is the problem. I'm trying to push off with my head faced up but I always seem to suck in some water for some reason and have to re-surface fast for air. 4.) I'm also having a hard time with the fast dolphin kick that most people use when coming out of a flip turn. I was just looking for ways/drills to improve in these areas. I just want to be able to swim at length instead of stopping constantly. Feel free to share. Also, any help would be greatly appreciated:afraid: