I've got my car rental, airline, hotel and rideshare apps all connected to the service I use, and when I eat out or take a taxi, I upload a quick photo. When my trip is over, my expense report is ...

Yet, many people aren't able to save as much as they'd like to in their 401 (k)s. Many don't save anything during the early years of their career. But it might still be possible to catch up.