If your pup is just five months old, I wouldn't worry about it too much. It takes time to build a strong working relationship. With lots of practice and interaction and bonding, your approval will come to mean more to your pup.
In the meantime, if he likes food and toys, great! You have lots of other reinforcers to choose from and can use those not only to reward him for desired behaviors, but to build up the value of praise as a secondary reinforcer. Combine praise with other things he likes (food, toys, little games with you such as Tag) and, over time, praise will become more meaningful.
It can be helpful to keep in the back of your mind that a secondary goal during your reward sessions is to make praise more valuable, so for example, instead of just popping a treat into his mouth to reward a successful cue, you might break that treat into several smaller pieces and feed him continuously while also praising him the whole time. Stretch what could be a quick one-and-done moment into a more pleasurable experience that is combined with praise.
As for not being able to toss a ball, what if the ball is tied to a string and you can bobble it around in the air or whisk it along the floor? There are several tug toys that have this design, and it might allow you to use a ball for play without pushing your dog into other dogs' space.
ARCHMX TDCH Pongu the Insane, CD-C, RE, RL1X6, RL2X5, RL3X2 (GSD mix, b. Apr 2010)
Crookytail the Tigerwuff, RL1, ITD (Akita mix, b. Jan 2011)