Why am I running out of storage so quickly?

[AC Question]

I have an LG Destiny, owned for 1 year. I have been noticing as I reach my 8 GB capacity it won't let me utilize a large amount of space. For example, I just recently attempted to install an app, using 26 MB of space, but my phone insists there isn't enough space! I checked storage, and there it tells me I have 675 MB left of storage free (internal, external I have 25+ GB.) What gives?