No need to force yourself. If I just finished an extra good book or series, I always take a break to come down and process.

It can also be tough sometimes to get going again. My advice would be to pick a book and finish it. Just read till you get bored or lose interest, put it down and come back later and pick back up where you left off. It doesn't matter if you only manage 5 minute chunks , it'll get easier with practice.