Heretic here with a quick thought. Every army has their own history and great sagas, but in each of them there is a great amount that goes unsaid. For instance, the Imperial codices generally talk about only a few battles in the Horus Heresy, namely the Drop Site Massacre and the Siege of Terra, and leave out the rest. This was supposed to be the end of the Great Crusade, when the Imperium was at its zenith and collapsed in on itself. There must have been more than those two battles. What I'm getting to is filling in the gaps.
I'm currently building a chapter of marines from scratch, as far as backstory; they aren't cannon so there's nothing I can draw on to give them a glorious past. But that also means there are no restraints on how my chapter can have gotten to where they are today. It may or may not be your cup of tea, but I'd suggest you take a few minutes and consider writing a backstory for your army. It really helps me get motivated to work on painting my models and makes me want to get some games in with them.
If a whole chapter isn't your style why not write a story about your favorite model's most glorious victory? Maybe some story of how the Great Wolf rose through the ranks or why your Hive Fleet is awesome. If your army is more exciting to you it might just give you another part of this hobby to enjoy in case you don't get the opportunity to play as often as you'd like.
