seconds

One year  =   60 seconds * 60 minutes * 24 hours  * 365 days   =  31,536,000 seconds

So....

1,000,000,000 sec  / 31,536,000 sec   ≈  31.7  years

Upshot : you will be lucky to live 3 billion seconds........and nobody has lived 4 billion seconds  [ yet ]