結構頑張ったって英語でなんて言うの？

Question

絵を描くのを結構頑張った

Accepted Answer

There are a ton of different ways to say 「結構頑張った」in English. Generally, you're safe using either of these:
 - I really tried hard.
 - I worked pretty hard.
 
 If you want really casual slang, I would go for this one:
 - I worked my butt off!
 
 For the situation you gave, you can use them like this:
 - I tried really hard on this picture.
 - I worked pretty hard on this picture.
 - I really worked my butt off on this picture!

Answer

「頑張る」→「To work hard, to put effort into」

「結構」→「Quite, a lot, really」

「I worked quite hard」
「I worked really hard」
「I put a lot of effort in」
という三つのフレーズで表現できます。
どれでも使えます。