I used to be a skinny guy, but I had a career change about 8 years ago (from construction to big truck driver) and my wife went home 4 1/2 years ago.
Both, I know, are elemental in the physical activity (or lack) I experience.
When I drive, I drink coffee and snack on carrots, cukes, etc (I'm going to change my name to Harvey)
Sounds like your diet is great...I also love rabbit food.
With regard to exercise, an old coach of mine told me that persistence is everything. The nice thing about being older is you'er not so much in a hurry. If you just do one push up a day and increase by adding one a week, within a year you would be doing 52 a day. The key to exercise is always adding on a little more time and variety of exercise and slowly build intensity.
No matter what you do exercise-wise, it changes your brain chemistry for the better and eventually become addictive (in a very nice way).
Best of luck with your program.