When I was 19 years old, I noticed that lots of the people I saw in their fifties were very much overweight. I reasoned that few of them were a healthy weight one year and put on 60 pounds the next. It seemed more likely to me that they gained a couple of pounds a year for 30 years, and by the time they decided to do something about it, it was just overwhelming.
I decided then that there were things I could do to burn an extra few calories a day that might add up to two pounds a year. Any time I go anywhere that is less than three floors, I take the stairs instead of the elevator. Now, if I'm with a group of people, I don't leave them, but if it's just me, or my family, I take the stairs. How many extra sets of stairs is that in a year? I spend weeks in hotels, so I'd guess 100 flights a year - times 36 years is a whole lot of stairs.
I never look for the closest parking space. If someone is backing out, I don't wait on them. I drive by, park further away and walk.
Whenever I'm on the phone, assuming I'm not in the car, I get up and walk. Unless I have to be typing notes, I get up and walk around the neighborhood (or if I'm in North Dakota and it's freezing outside, around the building). How many minutes a day is that? Some days it's only ten, other days it's over an hour. How many miles is that a day? Probably averages 3/4 of a mile times 365 days a year.
If I need to go anywhere - pick up a gallon of milk, mail a letter, deposit a check - if it's a mile or less, I walk. This annoys my youngest daughter to no end as she thinks she should be chauffeured everywhere. Some days I walk 3 miles or more, but unless it's raining, it's almost always at least half a mile, to pick up something.
I have a very sedentary job - sitting at a desk, in airports, on planes. So, I try every day to get in some exercise. I have an exercise bike in my living room and if I watch TV for half an hour, I'll ride the bike while the show is on. Almost every hotel has a pool, so I'll go swim for half an hour or so. And I teach judo once or twice a week. On a good week, I work out six days out of seven. On a busy work week, maybe only four.
My point is, if you change your habits NOW, you won't have to struggle with your weight for the next twenty or thirty years.
Think about it.