jacen,

Your story sounds very similar to mine only about 7 months later.  I have always been fairly active, Snow skiing in the winter, water skiing and softball in the summers and some rock climbing mixed in the free moments.  I tried to go to gyms but never stuck it out for more than a month.  For the past 3-4 years every March as the snow skiing season ended and before the water skiing season started I would take up running.  I would barely be able to get a mile at first but then work up to 3-5 miles in a couple months.  Then I would stop as my life got too busy.

I am a software developer by trade so I spend all of my working time at computer doing nothing to help keep me fit.  Like you, I had a love for fast food, and I still do.  I find it hard to give up but I am doing much better.  At the beginning of April I was 27 about to turn 28, 6 foot tall and 275 in a size 42 pants just like you.  In April, someone posted a picture of me on facebook and I was shocked at just how large I looked.  Even though no one would guess that I weighed 275+ and I was able to participate in just about any activity that I wanted, I realized that something had to change.  It was this shock that I needed to start my life on a path for change.  I slowly started making changes.

The first thing I did was to join a gym that is just a block from where I work.  Now, instead of eating every meal out for lunch, I was going to the gym for a quick workout over my lunch break.  I started bringing in snacks and small healthy meals that I would eat throughout the day instead of one large meal out.  I also replaced my daily bagel w/ cream cheese or donuts for breakfast with yogurt and granola.  One of the biggest aids in helping me choose foods and motivate me in this process was creating a spreadsheet where I tracked exactly how many calories I was eating and expending.  I was amazed at just how much and how unhealthily I was eating.  This helped make the changes stick even more.  At first I only really changed what I was eating at work and I saw some progress.  The next step I started making better choices after work when going out with friends for dinner and beers as well.

As far as exercise I started doing and upper body weightlifting circuit 3 days a week and added some Rowing for cardio 5 days a week over my lunch break.  I also started riding a bicycle with friends. We would ride 20-30 miles, 2-3 times a week.  Lately I have started adding in some core exercise routines to my daily workouts joined a recreational soccer team that some friends started and began running again.  For the running I signed up for a couple races to give me the motivation to keep working.  I am doing a 5k tomorrow night and 10k on Thanksgiving day.  I am now running between 9-10 miles a week plus the soccer with long runs around 4 miles.  My goal is to participate in an overnight relay race that covers 200 miles between 12 runners.  This year I drove a van for some friends who raced, next year I want to run in it.

Currently, I have lost nearly 40lbs, this morning I weighed in at 236.5lbs.  My size 42 pants are literally falling off of me and even my size 40 pants are very loose and I need a belt.  I can fit into a 38 but they are still just a tad tight. In general, during this time period I have tried to make modest gains in my weight loss.  I have been pretty consistent about losing between 1-2 lbs a week.  Sometimes I have a bad week but usually follow up with a good week.  I feel great, and get compliments all the time about my improving figure.  One of the hardest things for me that I learned through this is that what I eat is 100 times more important to weight loss than how much I exercise.  The exercising is great for my heart and allows me to do a lot, but I would still bet 260-270 without changing what I eat.  As far as running, just take it easy with something like the couch to 5k plan and don't over do it or you will get injured.  You will be surprised at how quickly you can work up to the 2 miles if you follow the plan and listen to your body.  Lastly,don't wait to start strength training.  Mix it in as cross training or rest days from running.  I try to work on body group about 3 times a week with strength training.  For cardio work I try to get work in at least 6 days a week but  mix it up between running, biking, rowing or some other form.

I literally have zero willpower, so if I can make these changes in my life then you can too.  The hardest part is being accountable to someone or yourself and to keep working even when you don't really want to.  Eventually it becomes easier as you learn to enjoy the activities and improvements in your life.  Hopefully like me you can find that motiviation that keeps you on track.  Good luck, you can do it.

Edit to add:

I forgot to mention that about 6 years ago I was smoking between 1/2 to a pack a day.  I had a similar epiphany when I couldn't do some of the things in my life that I enjoyed because of my lack of health due to smoking.  Even though I had tried to quit before I just decided one day that I really wanted to quit.  After that point I struggled but was able to keep strong and quit.  I still have urges today but they are mostly in check.  It is true that I gained a lot of weight after that since I essentially replaced my smoking with food.  But I know that if you truly want to change and you have the motivation to do it then you can make these changes.