To 50k Or Not...

Not sure at what point I ever thought running or hiking (more my speed) a 50K was a good idea for me.. I still struggle at a Half Marathon distance as far as efficiency is concerned. I mean my time does technically get better with each race I care to put my heart into but we're talking approximately 9hrs or more on my feet.. I have a handful of friends that have completed this distance but none that are relatively at my fitness level. Can I grit through nearly 20 miles over what I've put my body through to date??