Follow up from defence

So, during the recently passed weekend, I played a tournament and was drawn against first seed and during that game, I was doing well until I had to defend, I could take the defensive shots well as I’m tall but I’m also a decently fast player, but it occurred to me that I have no ability to follow up on my defence and change the rally back into my favour once it comes to playing against people with a strong attack.

My question to those reading this is what drills and corrections would you consider doing to allow yourself to make the difference needed to achieve a good follow up?

Thank you for your time.