I love reading. It is only through reading that I gain knowledge. It is only through reading that I gain humor. It is only through reading that I gain character. The fruits of my reading are my thoughts.
That being said, what does it mean to truly read something meaningful? This may be different for everyone. It may also differ depending on the genre-I do not expect a formal dissertation to make me laugh.
No, reading something meaningful means that whatever is being read resonates with you. For fiction, we are not simply reading a character's journey, they are traveling along that journey with the character. As the character grows, we do too. As the character matures, something in us does the same. When they cry, perhaps we may cry to. A great piece of fiction should make you feel something within you. Something similar, albeit slightly different, is true for informational writing or nonfiction. These works should provide you with something that you value, whether that be knowledge, skills, or just a deeper understanding of yourself and the world around you.
How about rereading then? Personally I've reread some books 1, 2, 3, or maybe even upwards of 4 times. Looking back however, the following reads are never as special as the first one, as one no longer has a sense of innocence in regards to the plot. The ending, the twists, the conflicts, the major points, etc are already known, which takes a lot of the meaning out of reading. In my mind, humans continue to read because it is in their nature to be inquisitive. They want to find out what happens next, they want to acquire more information to perfect a skill, they want to know more. Meaningful reading slakes one's thirst for more information and allows one to continue reading as much or as little as they desire. Rereading can be meaningful though, if one is looking for things they missed the first time around, or if one genuinely enjoys the subject or a certain character.
In summary, meaningful reading, at least to me, should resonate with the reader and make them want to know more. Hopefully this means something-to future me, or to you, my reader.