Single pilot IFR & pilot fatigue

I’ve been thinking about pilot fatigue recently.  I’ve been known to push the boundaries when it comes to what’s achievable, but surely there’s a limit. 

When you go flying, it’s very easy to be wrapped up with all that’s involved and not listen to your body.  On a review of this recent trip to Perth in Scotland, I noticed the tell-tale signs of my fatigue.  Is this an issue that you’re aware off, and how do you manage it?  Do let me know.