I know what you mean about family and friends. Too often they are very resistant to any changes.
What you can do is like elvislover says, start small and slowly build your way from there. I cut out all sodas from my everyday life, and I can tell the difference now when I did have the occasional soda. I'm winded, can't get up the stairs easily, etc. Plus, I actually lost a few pounds just from dropping that soda habit.
Secondly, start exploring with food a bit to see what healthier alternatives you can make. For instance, instead of that heavy, calorie ridden Mexican dish, what can you replace in it that will still taste just as good with the original ingredients?
Check out some Mexican cookbooks that are designed to be lighter in fare. They can help you figure out how to modifiy some of your dishes. You don't have to do all of your dishes light, but some changes here and there do add up over time, and may even save you money too.
Thirdly, go get a blood test to check your vitamin levels, etc. You may be low in Vitamin D, etc, which can really affect your mood and get you depressed. (I had mine checked after the doctor noticed I was really depressed, and I had almost nonexistent vitamin d and iron levels. So they put me on some strong pills and it really made a difference in giving me energy and outlook on life.)
And lastly, try to see what exercises you can incorporate into your day. You could start with buying a pedometer to count how many steps you take a day, and try to challenge yourself to meet that 10,000 steps goal.
Baby steps are really important because if you can stick with these, then you're more likely to stick with it for the long haul when you start really getting into it. Hope this helps!