It happened to me in February 1992, on holiday in the Canary Islands. I had just bought a new video camera and my wife was using it as we sat round the swimming pool. I was sat on the edge, dangling my feet in the water, talking to another holiday maker at the time and on playback I was shocked that you couldn't see my swimming trunks for my belly. When I got home I immediately started to change my eating habits. I knew going hungry would fail miserably, so I decided to just cut out the bad things in my diet and eat some good alternatives. We already had a good normal food regime, fish, chicken, rice, pasta etc but puddings, cakes and biscuits had to go and I swapped all these for fruit. That was the only change I made and I never went hungry but almost two stones were lost before our next holiday in July. I started marathon running in 1996 and no matter what I eat I couldn't eat enough to put on weight. I joined a gym in early 2001, while still running, and my body fat content was 16% and my waist size had gone from a tight 34" to a comfortable 30".
Some pointers to follow that I think important are:-
1) Do not follow any crazy monotonous diet, e.g. cabbage, Atkins etc.
2) Do not go hungry or you will snack on crisps or other junk snacks
3) Don't be afraid of eating carbs, our body needs them for fuel
4) Try to raise your activity level
5) Get weighed regularly and record it. It gives you the incentive to continue
6) If you're desperate for a treat avoid fat. Jelly babies were my favourite
7) Have a day off from the normal meals occasionally. Boil an egg, have a jacket potato, eat some soup, have some wholemeal toast, scrabled eggs etc...
8) Whenever your feeling peckish, between meals, go for the fruit bowl. In it you'll find loads of things to satisfy yor hunger, bananas, apples, tangerines, pears, grapes, kiwis etc. Don't bother about the calories in fruit, they just don't count... from experience.
Do it... do it now and don't dwell on whether to do it or not. Success will take a week or two to kick in and then you're home and dry.
Best of luck... Alex