His enthusiasm must have paid off on the training pitch, with the Chiefs loose forward being a surprise inclusion in the All Blacks' 31-man World Cup squad.
Jacobson was sitting alone in his Hamilton flat watching the televised squad announcement with hope but no inkling as to whether or not his name would be called out.
As the squad was named in alphabetical order, he began working out where his name might be called. After Rieko Ioane's name was announced, Jacobson got a once in a lifetime thrill.
"I'm on top of the moon," he said of being selected.
"I didn't back myself but I didn't write myself off either … I felt I had done the best I thought I could do so I was happy with that. Even if I did miss out it was 'alright, it wasn't because I didn't put out my best effort'. I was real nervous this morning and last night as I thought any little buzz on my phone I was pretty scared of looking at.
"There were a few fist pumps going around. There were a few things said to nobody."
Jacobson was the eventual beneficiary of Liam Squire ruling himself out of contention for the Rugby Championship and coming to an agreement with Steve Hansen that he would only be available for the World Cup as an injury replacement option.
Hansen addressed Squire's position after the squad was named and, although he wouldn't go into specifics, said it was a decision he and Squire reached together.
"We had a phone call, a really good phone call actually, and discussed things. Whilst Liam is playing really well for Tasman and really enjoying his rugby, at the conclusion of the conversation it was agreed that he would make himself available if we required him as a replacement."
With the agreement reached with Squire, Hansen said Jacobson was selected ahead of more experienced players Jackson Hemopo and Vaea Fifita because of what he brought to the pitch.
"If you're good enough you should be available for selection. He's a former under-20s captain so he's got good leadership skills, defensively he's one of the best hitters in the game, he's a good ball carrier, and he's just a smart rugby player," Hansen said.
"It came down to Vaea and Jackson then competing with Luke … and we just felt that Luke brought a little bit more than the other two to that position."
His hard-nosed style of play does come with its downfall, as the 22-year-old has been nursing a concussion recently after picking up a head knock while training. However, after a dominant performance in the National Provincial Championship at the weekend, Jacobson said he was confident any lingering effects of the most recent knock were well behind him.
"I just had a little bit of a setback but bounced back to normal pretty fast. I'm feeling good as gold now, no worries.
"I'm really excited by the opportunity and to have eight weeks together with the team you're going to form some pretty close friendships, I'm going to be learning heaps in training, I'm locked in for 8 weeks so I'll be in there training with the best … well, hopefully eight weeks.
"Any little chance I get I'll be going 100%."
- Christopher Reive