I've been there myself. I turned 30, weighed 205 lbs (at 5'8"), had a BMI that classified me as obese and was staring down the barrel of diabetes and heart disease.
I took stock and wanted to change. It's been 6 years and kept the weight off. I continue pursuing the optimal "me," where I eat and perform at my best.
I am writing this so others that are currently in a similar situation and want to change can have a starter resource. I should also note that I am not a doctor so I don't have exact scientific principles on some of these techniques. Also, make sure you consult a physician before drastically changing anything.
Weight Loss 101 (Small Changes)
Water obviously has zero calories, but beyond that water keeps us hydrated which helps circulation of blood and the flushing of any toxins or extra nutrients in our bodies. Less soda, juice and coffee.
You know when you are on vacation and sleep until you naturally wake up? What is that? About 8 hour-ish? Lack of sleep throws off our metabolism, makes us crave stimulants in the morning, then we drink more stimulants after lunch, then we can't sleep that night. Vicious cycle.
24 hours in a day, right? Well, fit in 30 minutes of exercise in a day and you can increase your life expectancy. Perhaps a post dinner stroll or a nice walk at lunch.
Weight Loss 201
If you really want to be aggressive with weight loss you need to burn off the fat. Plus, why not be fit? Perhaps you will be less prone to injury from minor mishaps.
The key for weight loss is to sustain your height rate in an Aerobic heart zone (roughly 130-140 bpm or light exercise, should still be able to have a conversation). Walking is fine, running will burn it faster than walking, swimming will use more muscle groups, and cycling is great because it is low-impact on your joints and it is possible to go for a 1-2 hour bike ride without feeling wooped.
Weight Loss 202
Tracking is great because you can start to see approximately how many calories you burn during exercise. Beyond that, I am inspired by racing myself. What is my best time on a route? How many miles did I go in a week? Can I beat that?
Websites like mapmyride.com, nikeplus, livestrong.com and Strava.com offer online and apps that enable you to easily track your exercise, even using the GPS on your phone.
Eat your Veggies
No more soda
Weight Loss 301
Eat whole foods