You should start off by saying what the sport is. I know you mention it later on, but the word ‘this’ doesn’t refer to anything yet. It’s only going to confuse the reader.

“I have been playing this sport ever since I was five years of age. My hobby, and most fun sport, volleyball.”

The second sentence is a fragment and grammatically incorrect. It might be better to say “The sport which I consider to be the most fun is volleyball.”

“I Love playing volleyball because I love the feeling you get when you hit the ball over the net. Even if you don’t get a point its still good to know you tried your best. At my school (*****) we have to wake-up at six in the morning to go to volleyball practices!”

I would begin a new paragraph with “At my school…” because it’s a new train of thought. You were talking about the feeling you get when you play, but now you’re talking about how volleyball teaches you not to be lazy. Also, you need a comma after “At my school (*****)”.

“It teaches us to be on time and to stick with the team and not me be lazy.”

Too many conjunctions. Your sentence would read more easily if you said, “It teaches us to be on time, to stick with the team, and to not be lazy.”

Hope this helps!

Maybe consider this to replace your third sentence: Volleyball is not only the sport I think is the most fun; it is my hobby.

Use this:

Even if you don’t get a point, it is still good to know you tried to do your best.

Try this for your last sentence:

It teaches us to be on time, stick with the team, and not be lazy.

Don’t forget to space after your periods.