To look back on something means to think of an event in the past or to remember something in the past. You can look back on your childhood, for example or look back on a memory. This is a phrasal verb used in both social and professional contexts.

1. Things are difficult at the moment, but one day we will look back on this period of our lives and laugh!
2. He has never looked back since leaving his small town and making a fresh start in the city. Now he has a great job and a lot of friends.
3. She looked back on her school years with fondness, but also regret. She had a lot of fun but would have liked to have studied harder.

1. Looking back on the work I did on that project, I can see now where I went wrong. I should have delegated more.
2. When I look back on when the company first started I can't believe we achieved as much as we did with such a small team.