Strengthening felt?

[exliontamer.livejournal.com]

Hi all. I'm a long-term reader, but this is my first post, blah blah blah. Basically I've made a messenger bag out of felt, which I'm very proud of because I've sewed pretty patches on it and things, but the felt below the straps is already getting very thin from the strain of carrying books and things. What would be the most effective (and easy) way to strengthen the bag and stop this from happening? Thanks in advance for any help.