Here are the completed sentences:

6. I like fish; I can't eat it every day, **although**.

7. I got a good salary as a health instructor; I gave up my job **in spite of** that.

8. You shouldn't eat much dark chocolate; **although** dark chocolate is good for your health.

9. He eats a lot of beef, **though** he knows it contains a lot of cholesterol.

10. Junk foods don't contain many nutrients; **despite** this, many young people still like to eat them.