I know a lot of people who are skinny and athletic will be saying to jog or work on cardio but thats not honestly easy to start...it hurts. I walked. I walked a lot. When I decided to make a change I walked about an hour a day and twice at 45mins on the weekends. Using an IPOD or cellphone with music makes time go by. If you have a treadmill you can watch tv shows on DVD and tell yourself you can only watch it when working out.
2) DRINK WATER...
keep yourself hydrated and get used to drinking it. It helps you keep hydrated and flushes some of that ucky stufff out.
EAT LESS MORE...smaller meals makes a bug difference, mix in some salads instead of bread. I found that the 1 calorie spray dressing at the store is FREAKING GOOD(seriously). Try to eat more protein and less fat, I ate a lot of chicken breasts with different seasonings. My favorite was taco seasoning on chicken breast, then wrap it in foil and bake. I could eat it by itself of mix it in a salad.
3) CUT THE CARBS AFTER LUNCH.
I am a busy girl and I would often eat a lean cuisine or weight watchers meal for breakfast. At lunch, a half sandwich/salad and little to no carbs after that. That is based on the fact we can only process so much carbs...rest will hold us back from the weight loss we need.
If you follow these your life will change. I was so happy when people actually referred to me as skinny and you will too.