Dr Denniss stopped by his old school during the Albion Park to Thirroul leg of what some have described as one of the greatest running adventures in the world.

Many have likened his achievement to that of another Tom (Hanks) in the movie Forrest Gump.

Nobody yesterday had anything but positive words to say about the humility and determination of the man who has spent 18 months circumnavigating the globe.

PHOTOS: Illawarra's Forrest Gump arrives in Illawarra

He had already run more than 26,100 kilometres when he ran through the gates of Lake Illawarra High, his longest ever journey to school.

The last 5000 kilometres across Australia have taken him just under 100 days.

They are the kind of numbers that have left everyone in awe of his achievement.

But what impressed many yesterday was how fit and energetic he still looked.

Cross-country runners from the school had little trouble keeping up with his steady pace while others struggled, but all were excited by his return.

So much so that Dr Denniss's main focus yesterday was on his family and all the people who had come out to encourage him as he headed into the final three days of his amazing feat.

But Dr Denniss has approached the whole journey by just putting one foot in front of the other.

After visiting his old school he caught up with his brother Paul before running over Windang Bridge with his sister Linda and then called in to see his mother Eileen before heading north.

Dr Denniss said he was happy for more people to join him today as he crosses another scenic bridge.

"I will be running across Sea Cliff Bridge mid-morning and then up through the Royal National Park to Waterfall," he said.

"I might even get to about Engadine."

Dr Denniss said local media attention had resulted in more people tooting their horn and waving.

But the best thing about yesterday was catching up with so many familiar faces.

"It has just been fantastic," he said.

"The whole day has been great but I guess the biggest surprise was seeing my year 5 teacher," he said.

"I haven't seen her for almost 40 years and I still recognised her."

Fay Holbert said she taught Dr Denniss at Warilla North and had been following his progress around the world.

"It was Tommy Denniss by the way back then," she said.

Lake Illawarra principal Tony Hicks officially welcomed Dr Denniss to his old school by handing him a rugby league jersey.

"It is good to see an old boy do so well," he said.

Student Lani-Rose Pettit, who turns 13 this week, said yesterday's experience was one she would always remember.

She said it was fairly warm for a run but that did not matter.

"It was really inspirational to be running with such an amazing person," she said.

Dr Denniss said he was not thinking about Friday's finish at the Sydney Opera House just yet.