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.'

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

What does man love more than life, hate more than death or mortal strife; That which contented men desire; the poor have, the rich require; the miser spends, the spendthrift saves, and all men carry to their graves?

What came first, the chicken or the egg?

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

What work can one never finish?