https://www.youtube.com/watch?v=xY2yajGqHhI 2:55

I can't explain any better than this from the British Council learn english website: Past habit – used to/would When we talk about things that happened in the past but don’t happen anymore we can do it in different ways. Used to We used to live in New York when I was a kid. There didn’t use to be a petrol station there. When was it built? We can use ‘used to’ to talk about past states …. I used to go swimming every Thursday when I was at school. I used to smoke but I gave up a few years ago. … or we can use ‘used to’ to talk about repeated past actions Remember that ‘used to’ is only for past states/actions that don’t happen now – we can’t use it for things that still happen now. Would Every Saturday I would go on a long bike ride. My teachers would always say “Sit down and shut up!” We can use ‘would’ to talk about repeated past actions. Often either ‘would’ or ‘used to’ is possible. Both of these sentences are possible. Every Saturday, I would go on a long bike ride. Every Saturday I used to go on a long bike ride. However, only ‘used to’ is possible when we talk about past states. We used to live in New York when I was a kid. We would live in New York when I was a kid. Hope that helps, this is an interesting question, I have never needed to explain it in all my years of teaching ESL. Thanks.

"Would" seems like there's no chance for changing and u will do that thing because of your instinct,it's always the same occurrence,the same story ,the same ending ,even u go back to the past.I think "used to" is better.

Thanks for the reply . But sorry , I'm still struggling to get what you mean exactly . Do you mean I could say : " I would watch cartoons all the time in my teens ." Is it right ?

.. in my teens. <-- try this.