What common phrase is represented by the below lines

Easy going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Medium going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Tough going:
Weak, 'I can't do it, I'm staying!'
Tough, 'Let's get going.'

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

What can go up a chimney down, but can’t go down a chimney up?

What country can make you shiver?

Can you make a fire with just a single stick?

A bomb goes off.
Carnage.
One person, only a few feet away, survives! How can this be?

The cream is heavier than Milk. True or False?

Peter wakes up daily to pick up his cycle and crosses the border between Spain and France daily with a bag on his shoulder. He is investigated daily by the officials but they don't find anything suspicious.

If we tell you that he is smuggling something what would it be?

If I put in one bird per cage, I have one bird too many. If I put in two bird per cage, I have one cage too many. How many cages and birds do I have?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?