Survival of lone man on hostile alien world

[Tmac]

I'm looking for a sci fi book from probably the 70's, maybe early 80's. Memory is a bit hazy but it has similarities to Sentenced to Prism by Alan Dean Foster, which I just read hoping that was it. The gist is there's a lone man (explorer? Crashed on planet?) who has to make his way across the planet, making big physical changes to himself to survive, and when he gets to his goal it turns out it was some kind of test, moral or physical. Vague I know, but it was a long time ago. Tried for years to find it

 

[yodachan]

Pretty sure this is "Threshold" By David Palmer. See this thread from 2008. Alone on an alien planet

 

[Tmac]

Thank you very much, I think you're right. Have ordered it from Amazon so I'll know for sure in a couple of weeks. It's driven me nuts for nearly 30 years trying to remember enough to find it