Read without understanding
When it comes to learning a new language, reading is a close second to listening. But it can be challenging to practice.
You need to find content that perfectly matches your current proficiency level in that language and still be "interesting" to read. Educational material is limited (and expensive) and not always entertaining. Children's books are either too easy to read or utterly irrelevant to daily life.
On top of that, looking up in a dictionary whenever you encounter a new word is exhausting and discouraging. You spend more time jumping back and forth between your reading material and the dictionary than doing the actual reading.
Solution: read what you know, ignore the rest
Do you remember when you first learned to read in your native language? I don't either. But if you look attentively at how children read, you'll notice that they focus on the words they recognize and ignore the words they don't (or wait for an adult to read them for them).
Pick any text (book, article, manga) and practice reading the words you already know so they become effortless to read. Acknowledge the words you don't know WITHOUT looking them up in the dictionary, and move on.
It will make reading less cognitively straining and build your confidence over time. Eventually, the words you know will be so effortless to read that they'll feel as if they were in the background, quiet and supportive. The energy saved will allow you to focus on the words you don't know when you decide to practice understanding.
It will also train your predictive capabilities. Our brains are prediction machines. When we read or listen to a conversation, we are not passively waiting for the next word. We are actively predicting the story. Every time a new word arrives, our brain compares it to what it had anticipated. If it's a match, a feedback loop is strengthened. If it's a miss, the brain becomes more attentive.
Have you experienced this weird phenomenon when you learn a new word, and suddenly, you start hearing people using it around you? It occurs because when you listen to a conversation, your brain fills the gaps in your understanding by predicting its meaning. Of course, people had been using that word all along, but somehow, your brain didn't need it to make sense of the conversation and was ignoring it.
Read without understanding
The key to practicing your reading skills is to focus on reading and not understanding. It is okay if you don't understand what you are reading. If it feels weird, you can always imagine (predict) what it means.
It's like karaoke in a foreign language. You're not really trying to understand the lyrics, but that's not stopping you from having fun. In fact, karaoke has been a tremendous help for me in practicing effortless (and fast) reading. Plus, it improved my popularity during memorable all-nighters in Shibuya ... but I digress.