Inner meaning for Jihad?

For a long while now, I've thought of jihad as having an understanding for internal spiritual struggle. Really, any religion that mentions a spiritual struggle of any sort, I usually filter it through this prism. But I am wondering if there are either popular interpretations that state Jihad is an inner battle (within mind/heart of the believer), or if there are lesser known sects that base their understandings of Jihad on such an internal struggle?

I felt like I had answers to this about a decade ago, but looking for an update from practicing Muslims.

Jihad is a struggle in the path of Allah, whether it was physical or a spiritual one. So, it's not only spiritual. All struggle to defend one self or spread justice is Jihad.