1. First of all, Daniel should stay away from food containing a lot of sugar. (Page 38)
stay away from: 离开，远离
As he has been ill he has stayed away from work for the past week.
Ask the children to stay away from the fire!
contain verb to have something inside or include something as a part:
How much liquid do you think this bottle contains?
I've lost a file containing a lot of important documents.
Try to avoid foods which contain a lot of fat.
The allegations contained in this report are very serious.
2. I also think that Daniel should break the habit of sleeping until noon at the weekend. (Page 38)
break: verb [I or T] broke, broken to destroy or end something, or to come to an end:
Eventually someone spoke, breaking the silence.
She laughed and that broke the tension.
The enemy were unable to break the code.
She broke the record for the 5000 meters.
Outside workers were brought in in an attempt to break the strike.
They tried to break his will but he resisted.
He thought she would break under the strain.
3. He said that he was trying to quit doing there, but it seems that he has not been able to yet. (Page 38)
quit: verb [I or T] quitting, quit, quit to stop doing something or leave a job or a place:
Would you quit your job if you inherited lots of money?
[+ ing form of verb] I'm going to quit smoking.
Quit wasting my time!
Press Q to quit the program.
He has not quit smoking, but is holding down to three cigarettes a day.
One friend of mine has decided to quit his highly-paid but demanding position in his company recently.
4. I think that Daniel will give up his bad habits, but it will not happen overnight and it will not be easy. (Page 38)
overnight: adjective, adverb
(1) for or during the night:
an overnight stop in Paris
You can stay overnight if you want to.
(2) suddenly and unexpectedly:
She became a star overnight.
The book was an overnight success.