3 years ago I moved to Egypt sold my ponies and moved on to horses... How can I bring back my joy for the sport ?

Do the tings you used to. Just spending time with your horse and riding for pleasure, without and goal in mind, just feeling the connection with your horse. On the flip side, it could also help to go into a ride/training session with a small, easitly attainable goal in mind. When you achieve it it'll make you feel proud and accomplished as a team.
You could also try doing some liberty work with them, that way you'll feel better connected and motivated as partners.