take it in small batches. Sometimes it's easier to just say, "i'll read 30 mins/1hr" or whatever and just do that every day (usually at a set time helps) and you can knock out quite a bit. Thing is too, sometimes theory gets hella interesting and you'll keep wanting to read. when things start clicking, i always want to keep reading a bit so that 30mins turns into two hours easily without realizing it.

some theory is daunting with how big it is if you don't read long things much, but just set small goals like a time or # of pages, good luck dude