Labour is hard work.
You can labour over something.
A labour of love is something that is hard work but brings a lot of satisfaction.
'Rebuilding his classic car was a labour of love.'
However, there's another meaning of labour, also relating to hard work.
When women are about to have a baby, they 'go into labour.'
Here's the beginning of a French comedy film called Taxi which combines a man who loves his work with a lady in labour.
Fasten your seat belt first!