The new inquests heard Stuart Gray gave John McBrien, of Holywell, Flintshire, heart massage and chest compressions.
But the health worker said the 18-year-old was in a "desperate state" and he was "fighting a lost cause".
Ninety-six fans were fatally injured in a terrace crush at the FA Cup semi-final in Sheffield on 15 April 1989.
Mr Gray, who was the general manager of Kidderminster district health authority and had some first aid training, told the jury he remembers the disaster at the Liverpool v Nottingham Forest match "as vividly today" as he did 26 years ago.
He reassured Mr McBrien's family he did not leave the A-Level student's side.
"John was lying at my feet. I was sitting up myself, I don't know how I got there. When I came to he was lying at my feet, lying on his back," he said.
"I was aware of the fact that it was probably fighting a lost cause, but the point was that he was there and I was just trying to do what I knew was the best thing I could do to see if I could get him breathing again."
He said Mr McBrien was "in a desperate state" but added: "I thought that if I got some air into his lungs and I could at get his heart going again, there was at least a chance he may have survived.
"So I just kept going, giving him heart massage and compressing his chest for maybe about five minutes."
Mr McBrien had a place to study at Liverpool University and his mother, Joan Hope, described him as a "kind, generous and charismatic" son who "excelled academically".
The inquests, in Warrington, Cheshire, continue.

The comments sent the value of the US dollar higher, which hit the price of oil and other commodities.
This affected shares in mining companies, who were among the biggest fallers in the UK market.
The FTSE 100 fell 112.45 points to 6,053.35. Fresnillo dropped 7% and Anglo American dropped 4.5%.
Shares in oil companies were also lower, with Royal Dutch Shell down about 4%.
In the FTSE 250, shares in travel company Thomas Cook sank nearly 19% after it said summer bookings had fallen.
The company said holidaymakers were avoiding Turkey because of safety fears, while travel to Belgium had also seen a "sharp decline in demand" after the Brussels attacks.
The travel sector was also under pressure following the news that an Egyptair flight carrying 66 passengers from Paris to Cairo had disappeared.
Shares in travel firm Tui dropped 1.7%.
On the currency markets, the pound was boosted by news of stronger-than-expected retail sales growth in April. Sales volumes rose 1.3% from the month before, according to official data.
The pound was down 0.1% against the dollar at $1.4584, and 0.03% higher against the euro at â‚¬1.3017.
A Liverpool fan who lost consciousness in the crush at Hillsborough told the inquests he "came to" and began trying to save a teenager lying next to him.
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(Close): The market dropped sharply as investors reacted to comments from the Federal Reserve which suggested a US rate rise could come as soon as June.