I'm 65, 6ft, weigh 170-175 depending on miles pedaled to donuts eaten. I'll give you this advice:
1) Give up soft drinks, regardless of diet or regular. This includes sports drinks.
2) If you drink alcohol in any form, seriously restrict your intake. Lots of calories there.
3) If you have a sweet tooth, likewise restrict your intake of sugar, which is in nearly all food that comes in a box. Don't add sugar to coffee, tea or anything else.
4) As recommended above, journal all food intake, and read the labels to see what you're actually eating.
Some people have success with ketogenic (carbohydrate restricted) diets, eating mostly protein. I'm going the other direction to mostly vegetarian with occasional chicken, but this is a recent development. Like you, I have always eaten anything I wanted. I recently "discovered" the concept that better nutrition might help me in my aging process. This approach may help you, also.