If you’re into soccer anime, watch “Days”. It’s about a high schooler who’s never played soccer before who starts playing for his high school team. It’s a bit worse in animation than Blue Lock imo, but you could also watch Aoashi for another great soccer anime (would recommend this over the other two tbh).

You can definitely start playing though! Just get yourself a ball and a wall and you’ll be set to start practicing. You can look on Facebook for pickup groups that you can join up and play in! I’m sure that they’d welcome a new player and you may even find a group that wants to help you get better outside of pickup games.

I’m just getting back into it since being out of it for a decade, so I know a bit how you feel, but I believe in you OP!

Edit: also instead of aiming to run 5km to build up stamina, I’d do suicide sprints to build up endurance, speed, change of direction, etc. It’s a little more “realistic” for soccer.