I can back up what PP says.
DHL is a good employer, but it is a lifestyle that you love or hate.
I quite enjoyed it, but did only last about 20 months before I moved back to charter flying. However, I hate that even more, so am now doing scheduled long haul for a certain UK airline.
I didn't find it tiring at DHL, but some guys did who struggled to sleep.
Think carefully if you like nights, they do age you rapidly.