Jumping up can be due to afection(although it doesnt seem that way because of his size, but think of him as a little toddler and you will understand), anxiety, excitement, playfulness, anxiety due to separation, eagerness to please the older pack members, etc.
Nothing that cannot be trained out of him without using force.
Stosh is right, keeping him away from his family(his pack members) will only make it worse.
We have a 13 month old male too. 3 -4 KM is barely enough exerecise especially for a dog that is as. active as you are describing. Lots of fetch, jogging, walking and training will tire him out though. This age is difficult but once you invest the time and patience needed in training at this age, you will have a wonderful dog. Its like teenage years.
For now, you can do a lot of ball play, running. And dont just feed him his meals.
Do NILIF. Nothing in Life is Free
And this : Mind Games (version 1.0) by M. Shirley Chong
Here are some positive training video channels:
(you will find many other videos by the same person on various training topics.)
To teach prolonged sits and downs, start when the dog is hungry, and have him sit . say yes! and feed him a treat. then feed him another. wait a second feed him another.
Release him and then call him back and have him sit again and do the same. Gradually increase the time between the treats. Same with down. It will seem like a long way to go, but you will see progress. And he will be lying down for minutes and then half hour with intermittent rewards and then no rewards at all.