I have no choice but to read, and read, then to read some more. It's frustrating in the sense that you can't feel any progress. It makes you sick looking up the same word for the tenth time, doesn't it? But if you bite the bullet and just carry on, your vocabulary will grow dramatically in a year. Then it turns into pleasure, unbelievably.
Spanish is my second foreign language; when I had been studying English, there were just the dictionaries on paper, and none of your Duolingo; I was younger then, though
I've got just 2.5 years of daily Spanish studies, consisting of Duolingo, no less than 2000 pages of plain fiction (half of them in the last eight months) and less than two hundred questions here. Nothing more. I can't speak, of course, yet I can read without sinking into depression. If nothing bad happens, in a year I will be a happy reader.
Of course, total immersion among people that can understand only Spanish is better still.
UPD
When I decided to really learn English, I made a list of the approaches which won't work (based on my high school experience). So I keep no records, and keep artificial exercises to a minimum. Of the natural practices there are but two: talking in dead earnest, and reading.
A note on reading: choose fiction with a lot of dialog; don't stick to one author, as the personal vocabulary is always limited and idiosyncratic.