**V + 다 보니, **the shortform of 다(가) 보니(까) is used to show that you've learned or realised something new after repeating an action for a long time in the past:
매일 운동을 하다가 보니 지금은 근육이 생겼어요.
I exercised every day and now [I realised that ] I have muscles.
주말마다 친구들과 과식을 하다가 보니 몸무게가 늘었어요.
Every weekend I overate with my friends and now [I realise that ] I've put on weight.
매일 한국말 연습을 하다가 보니 지금은 한국말을 잘 해요.
I practised speaking Korean every day and now [I've found that ] I can speak it well.
매일 쉬지도 못하고 일만 하다가 보니 피곤해 보여요.
Everyday I just worked and didn't rest and now [I realise that ] I look tired.
매일 같은 신발을 신다가 보니 신발을 망했어요.
I wore the same shoes everyday and now [I've found that ] they're ruined.
책을 조금씩 읽다 보니 한 권 다 읽었어요.
I read the book little by little and now [I've found that ] I've finished the whole thing.
한국어 이야기 팟캐스트를 계속 듣다 보니 이해가 되었어요.
I kept listening to the Korean story podcast and now [I've found that ] it makes sense to me.
오래 혼자 살다 보니 익속해져서 이제 누가 있으면 불편해요.
I've lived alone for a long time, so now I feel [I've found that ] uncomfortable with someone.
지난 밤에 친구들이랑 술을 마시다가 보니 귀가 시간이 늦어 졌어요.
I was having a drink with my friends last night and then [the next thing I knew ] it was way past the time to go home.