A race with history
The first Boston Marathon took place in 1897 when, inspired by the Olympic Marathon in Athens the previous year, the Boston Athletic Association (BAA) staged a race from Ashland to Boston. Fifteen runners started. Local sportswriters adored the marathon; it let them unleash their most colourful phrases. "It must be spring," they wrote. "The saps are running again."
Entry numbers remained steadily in the hundreds as the decades passed. It was only in the late 1960s that applications breached the 1,000 mark. In order to slow the marathon's growth and preserve it for competitive runners, the BAA decided in 1970 that runners would have to provide a written declaration, signed by a coach, that they could break four hours.
The following year you had to prove you'd already run 26.2 miles in less than 3:30 - and the BQ was born. Since then, the qualifying standards have changed nine times by the organisers (they are now age and gender graded) as a way of controlling the size and makeup of the field. They are set to change again in 2013, becoming tougher still.
The going gets tough...
At mile 12, I can hear the women of Wellesley College before I see them. The roar can be heard from half a mile away and it gets louder with every step, building to a crescendo as the course straightens out in front of the college building. I have entered the 'scream tunnel'.
In one of the race's great traditions, the students of the all-female college turn out in droves to support runners with high-fives and an incredible wall of noise. Like sirens, they tempt runners with kisses - in the quarter-mile stretch I see signs saying, 'Kiss me, I'm a lacrosse player', 'Kiss a chemist' and my favourite, 'Kiss me! I'm going to be President one day!'
It is probably the most uplifting and downright funny support I've experienced and it's like an electric bolt of motivation. But I must resist the temptation - I don't want to miss out on a new PB because I stopped for a snog, even if it is potentially with the future most powerful woman in the world.
Warning: hills ahead
The course turns sharply for the first time at 17.5 miles, bearing right past the handsome red brick facade of Newton Fire Department - the start of the hills section. The first ascent is long but manageable. But my hamstrings are suffering twinges of cramp. I try to lengthen my stride to stretch out my muscles on the move.
The second hill rears up just past the statue of race legend and two-time winner Johnny Kelley. I get to the top and for a while my fatigue-addled brain thinks the worst is over. But three-quarters of a mile further on the road rises again, and chalk messages and drawings on the road confirm I am now tackling Heartbreak Hill.
My hamstrings are gripped by cramp again. I stop, stretch each leg and start back up the hill. Thoughts of a PB are fading fast - now it's just a case of finishing. The crowd roars encouragement to runners making the top, while a band and inflatable arch mark this intra-race achievement.
Thankfully the route almost immediately noses downhill, and continues like this for the next three miles. Exhaustion tends to demoralise me at this stage of marathons, so I resolve to not look at my GPS. But a glimpse of the Prudential skyscraper jolts me out of my trance - I realise that I am now just a couple of miles from the finish.
I work out I can afford to run the last two miles at a nine-minutes-per-mile pace and still bag a PB. I've been looking at little else but the road ahead for the last five miles, and it comes as a shock that I can still make it.
I'd like to say that I could relax and enjoy the sights and sounds of the boisterous downtown crowds - including fans of the Boston Red Sox baseball team, who always play at home on Marathon Monday and whose Fenway Park ground is metres from the race route. But the truth is I am stressed out, in pain and want the race to end.
The feeling of relief that washes over me after the final left-hand turn on to Boylston Street is monumental. I run under the blue finishing arch in three hours, eight minutes and 33 seconds. I have cut five minutes off my previous best time and I've done it in the world's oldest annual marathon.
This is an immense event that has got everything - great scenery, slick organisation, a brilliant atmosphere and an unmatched sense of tradition. My only regret is that in the pursuit of a PB I couldn't fully appreciate it in all its glory. Nevertheless, I received my medal and felt so grateful I could have kissed the ground. But I was worried that I wouldn't have been able to get back up again.
Want to run it?
The 2012 Boston Marathon is on April 16. Registration opens on September 12.
Find out whether you could qualify for the Boston Marathon and check out the tough race route.