Keeping Players interested in your campaign is almost as important as creating the campaign and story arc.  You maybe really proud of your campaign storyline as a DM but your players may not be.  It is important to not only try to to tell your story but to also keep the players engaged into your story by adding things  they want to see happen in the campaign/ story and how they want to see their characters develop.  Instead having to pester the players during the game or outside the game tell your players they can add to it by creating and maintaining player journals.  Make it optional but for those that do take you up on it your can use an incentive of in game rewards they can cash in or extra XP. 

Player’s Journals

I like to use Obsidian Portal to track adventures, especially if your games are far apart like a couple of months.  Obsidian Portal even has an option for the Players to create journals for the campaign.  Award players extra XP for creating and updating journals.  It does not have to just be about what happened in the game but characters reactions, hopes , fears and desires.  This is a great way for a GM to gauge a players interest in the campaign and where the player would like to see the game headed.  

Lore Master - 

You can assign tasks to players in game. The Loremaster can right down crucial information about monsters when the GM give out the info and answer questions for players who ask the same question over and over.  “Is the monster immune to fire?  Did we attack it with fire?  Is the monster immune to Acid?”  Lore Masters can also be used outside of combat to take notes on the game for the players and even the GM.  Sometimes the you get in the zone and forget to write down on the fly things like names of NPC’s or places and the Lore Master can keep track of these to send to etc group later.