Excruciating knee pain last Thursday forced the Wanaka charity runner to abandon part of his mission - to run 50 mountain marathons in 50 days.
On day 14, he accepted he would have to climb the peaks at walking pace and not complete the full marathon distance.
His assault on Ben Lomond on Friday was made doubly hard after good friend and fellow runner Steve Combe was killed the previous day.
''He [Combe] was our leader for the day for Monday.
''He's just an absolutely wonderful, wonderful human being who was a massive supporter of this project.''
Mr Law started to say it was inconceivable his friend would not be there today - but broke off, pointing to the sky.
''He is - he's going to be here.''
Mr Law is buoyed by the fact the High Five O challenge has raised more than $330,000 for the Mental Health Foundation.
His story's an inspiration for many, the challenge drawing support from around New Zealand and overseas.
Mr Law said he thought his body would have held up better.
''It's massively frustrating because after two years of intense training with not a single injury and very early on it lets me down.
''That's OK - I've got to just put one foot in front of the other, keep plodding, revise plans as we go, and do something worthwhile each day.''
Now, the focus is on the big picture.
''My pride's a temporary thing,'' he said with a grin.
''My pride will heal in time.''
