Sport

3. An official e.g. in football who is responsible for presiding over the game.
4. A surface on which tennis is played
10. To became continuously successful.
12. A "judge" in tennis
14. An endurance (noun)
15. A person against whom you compete
16. To reach a missed thing or e.g to make the time difference between opponents disappear
18. An injury in a joint caused by e.g. bad movement, usually accompanied by swelling.

1. "You shoul ... eating in fastfood restaurants if you'd like to loose weight."
2. "If you have the ..., I'll guarantee that you never fall down." (In form : ...of...)
5. A place in which boxers compete
6. To participe
7. An activity which is governed by certain rules and usually also of a some form of "judge".
8. "He is boxer who ... all comers."
9. To quit something
11. "If you want to succeed, you can't be satisfied with just being a ..."
13. A surface on which you could play hockey
17. A surface on which golf is played