Great Britain Olympic sailing hope Nic Asher has revealed he has been battling illness in recent months, but has vowed to fight for a London 2012 place.
In May, the 26-year-old was diagnosed with autoimmune thyroiditis, a condition where the immune system reacts against the thyroid gland.
"It was probably one of the lowest points of my life there," Lowestoft-born Asher told BBC Radio Suffolk.
"But there's definitely light at the end of the tunnel."
The two-time 470 world champion started the World Cup season promisingly with a win in Miami in January alongside team-mate Elliot Willis.
But he found it took longer than usual to recover and went on to finish poorly in April's Palma regatta.
Still concerned over his health in Hyeres later that month, Asher took blood tests in France which proved inconclusive.
It took two more tests to identify the problem but there was not enough time to arrange medication before last week's Sail for Gold in Weymouth, an event with a bearing on Olympic selection, where team Asher-Willis could only manage 19th.
"In Parma we weren't that far off but I could feel something was wrong," he added.
"It was really hard to concentrate and it's so hard to sail because it's such a mental sport."
Asher is waiting to see a specialist before deciding how to manage his condition.
The news is another blow to the pair's Olympic dreams, after missing out on Beijing three years ago when their build-up was hampered by an injury to Willis.
But with GB officials yet to name their squad for next summer, Asher is holding out hope.
"The timing of these things is a little bit frustrating, but it makes you a lot more determined," he said.
"This time it's not gone how we wanted it to again but we still have an opportunity to make it and get our gold medal."