If someone has a new lease of life, they have a new enthusiasm for living.
A pain in the neckInformal
You can say someone is a pain in the neck if they annoy you, or something is a pain in the neck if you don't like doing it.
A shot in the armInformal
You can say something is a shot in the arm if it gives a person or an organisation renewed energy or enthusiasm.
Do you the world of good
If something does you the world of good, it makes you feel a lot better.
Fresh as a daisy
If you feel as fresh as a daisy, you feel energetic and lively.
Ill at ease
If you're ill at ease, you feel tense or you can't relax in a situation.
Junk food
Food that is bad for us because it contains large amounts of harmful substances like artificial colouring, preservatives, salt, refined sugar, and so on.
Just what the doctor orderedInformal
You can say something was just what the doctor ordered when it was exactly what was needed.
Kick the habit
If you kick the habit, you manage to stop doing something that has become a bad habit.
on your last legs | on its last legsInformal
If you say you're on your last legs, it can mean you're close to exhaustion, or it can mean you're close to death. If a thing is on its last legs, it's close to breaking or wearing out.
recharge your batteries
You recharge your batteries if you do something to regain your energy after a period of hard work.