"It just shows me, if I can do this, I can do anything," he said.
At 43 years old, Sinclair, also known as Big T, has the legs of a 70-year-old. Arthritis, a blood clot and surgery scars plague him every day, but still, he charges on.
"I do find it hard. My legs feel like they are going to fall off all the time but it's mind over matter. I'll just push myself until I can't go any more," he said.
Sinclair has suffered from depression for years.
"I would sleep to 4pm to 5pm every day. Sometimes I'd feel like I don't ever want to get up. Sometimes, I've even wondered what it would be like if I wasn't on this earth."
What keeps him going is his 7-year-old daughter, who he sees each Friday. Her, and this goal.
Inspiration came from old high school friend Leslie Watson, who set himself a goal of 50 climbs but by last month reached the top of Mauao 150 times, shedding 40kg off his 209kg frame.
Read more about Leslie here.
"When I saw Les doing this, walking up every day, it just shows that it doesn't matter how you look or where you come from, if you set your mind to something, you can do it."
Sinclair bikes from his home in Ōtūmoetai to Mount Maunganui every day. He admits his first climb, 50 days ago, involved "a lot of stops" and took more than an hour. Yesterday, he was up within 40 minutes.
"I still have stops going up but when I make it up, it's almost like breaking the chains. I feel so good afterwards, so happy. I feel relieved," Sinclair said.
"I don't know what it is. It's just so calm. I just relax up there and everything on my mind just goes away. It's like I'm somewhere else. It's magic."
When asked what he would do to celebrate, Sinclair said probably watch a good movie and dabble in something good - and bad - to eat.
"I'm definitely going to do more climbs," he said.
"I'm not done yet."
Where to get help
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111. Or if you need to talk to someone else: Lifeline: 0800 543 354 (available 24/7). Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7). Youthline: 0800 376 633. Kidsline: 0800 543 754 (available 24/7). Whatsup: 0800 942 8787 (Mon-Fri 1pm to 10pm, Sat-Sun 3pm-10pm). Depression helpline: 0800 111 757 (available 24/7). Rainbow Youth: (09) 376 4155. Samaritans: 0800 726 666.
