Mr Law's original mission for his High Five-O Challenge was to run 50 off-road marathons on 50 peaks in 50 days, starting with the Tarawera Ultramarathon on February 7.
However, a crippling knee injury early on forced a rethink. Some of his runs had to be cut short, but the 50 peaks in 50 days goal remained in place.
Media liaison person Vera Alves said this week Mr Law had continued to run as much of the daily marathon distances as he could and was now averaging about 33km per day, including a 51km day last weekend.
His knee injury had healed, but fatigue was now setting in.
''He's still running strong, he just feels very tired. He does not want to be getting out of bed any more ... [but] other than tiredness, he feels he's actually getting stronger.''
Cyclone Pam had also prompted changes to the original schedule, with some peaks being substituted for others last week.
Before he set out on his quest last month, Mr Law had already topped his original goal of raising $250,000 for the Mental Health Foundation of New Zealand, so he raised the bar to $400,000.
However, after returning from his 44th mountain on Sunday to learn the revised figure had also been reached, he promptly announced a third target of $505,050, with six peaks to go.
Yesterday, Mr Law bagged his 47th peak - Kohukohunui, in the Auckland region - with a group of supporters, covering 42km and nearly 2000m of vertical gain.
He will cross the finish line for the 50th and final time on Saturday in Auckland at the Dual marathon.
Yesterday afternoon, Mr Law's website showed more than $412,500 had been raised.
