As you're relaxing in the garden this weekend, or enjoying a quiet pint in a country pub, spare a thought for this Oxford man.
Hanno Nickau, 46, of Coppock Close, Headington, will be one of 48 triathletes taking part in the inaugural Double Iron UK event tomorrowAug2 - a test of endurance involving a 4.8-mile swim, a 224-mile bike ride and a 52.4-mile run.
The race - the first of its kind to take place in the country - is due to be held in Lichfield, Staffordshire.
The fastest competitors will complete the course in 22 hours.
Father-of-two Mr Nickau, an Oxford University lecturer and member of the Oxford Tri Club, said he realised the event might seem "crazy", but he couldn't resist.
He said: "It's very much a personal challenge and is about finding out what my body and mind can do. I know I will have to dig pretty deep.
"Compared to some of the other competitors I am probably undertrained, but I think my mental strength will get me through."
He is aiming to complete the distance in under 24 hours and is hoping for a top-five finish.
The swim will comprise 304 lengths of a 25m pool, the cycle is 16 out-and-back laps of 14 miles, while the run covers a 1.24-mile loop 42 times.
Sleep is optional for competitors - and is a luxury that Mr Nickau is choosing to do without.
He said: "I have decided that to get near my target time of 24 hours I won't stop for sleep. I will stop for about five minutes to eat properly twice during the bike ride.
"I'm trying to forget about the distance and just view it as a 24-hour event instead."
He will have a three-strong support crew with him, Oxford Tri clubmates Sue Turner and Paul Peros, as well as his 17-year-old son Simon.
Last summer, he undertook a similar feat when he completed Ironman Switzerland in Zurich - covering half of this weekend's distances - just a week after racing at Ironman Germany in Frankfurt.
Triathletes would usually leave at least two months between races to ensure complete recovery from the demanding distance.
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