My friend says to me : What did you tell him yesterday?
Me: I told him that I could do it when I was young and that I couldn't do it anymore because I'm old now.
Hi since I'm talking about something that I said in the past I changed Can to Could but I'm not sure If I should change Couldn't to can ( can't do it anymore) , should I keep couldn't and should it be I was old ? because it's something I said in the past so I'm not sure.
I read the other threads they're different from my question.