Imparfait vs Passé Compose

From an English point of view, I would say the tense used indicates whether the situation ended or is ongoing. In English it would be, 

"I've always struggled with maths" = this was true in the past and is still true - I continue to struggle with it

whereas the use of the imperfect would be:

 "I always struggled (I always used to struggle) with maths" = I don't struggle with it now / I'm no longer in that situation (either because you got better at it, or you simply don't have to do maths anymore!)

Perhaps one of our French experts can confirm if this matches the meaning difference in French?

To complete Rowen's answer, in this specific example:

- Using the Imparfait : "J'avais toujours du mal avec les maths." would indicate a past recurring fact, such as "I always used to struggle with maths."

- Whereas using Le Passé Composé here simply states a fact that takes its roots in the past (while continuing in the present)

I hope that's helpful!
Bonne journée !