My sister is an olympic level athlete, food as a reward becomes a problem for many of her competitors. Rewards help cement a habit though, personally I use music when I require extra motivation and don't when I don't need it. Maybe consider going to a req center and soak in a hot tub as a reward or a day off.
I think this is the same as writers block or failure of a painter or an athlete. Focus is lost and regaining it is not simple. I've worked through this process a number of times. I found treeplanting during the summers of my CPSC degree really helped rejuvenate me. The isolation, physical fitness, financial freedom and socializing was invaluable. I am replicating these things in my daily routine now. I have been taking it seriously, a regimented day:
6:00 wake up, put on clean laundered sweatshirt for run(comfy way to trigger my habit)
6:10 eat greek yogurt, maple syrup and vegtable juice
6:20 go for run, 10 min 120bpm warm up, 40min 130-140bpm then 10min 120bpm cool down. very light does not leave me tired for the day ahead and builds appetite for a significant breakfast
7:25 shower
7:35 make breakfast; eggs, butter, milk, tomato, kale, onion, oatmeal, sugar, green tea. This provides post run energy and fats provide a slow burn for the day.
8:10 10-20min rest, let your mind and body relax
9:00 get to work, I try to stand but also lounge with my laptop. I take breaks to juggle, do handstands or swing my home-made bulgarian training bag.
12:00 lunch, either a stew or lentles
12:30 another moderate rest, 20mins. I rarely sleep, that would interfere with homoeostasis and I don't generally feel the need
1:00 back to work until I lose focus. Make sure your space is compfy, live in a place with quality air(I live in Vancouver) use houseplants to clean air, a fan to circulate fresh air from outside, use curtains and plants and earmuffs to block out noise and light when desired. Be Compfortable! Eliminate odours, and I don't mean febreeze, I mean go to the source.
5-6:00 ish I'll go out with friends, some activity maybe do chores.
8:00 cleanup, dishes, wash floor busy none mental tasks.
9:00 personal email, facebook
9:20 bath w/ ebook, epsom salts seem nice
9:40 more reading
10:00 open window it's bedtime and a drop in body temp helps induce sleep which you must take seriously.
When we are young we can ignore discomforts, but stress accumulates and I believe the impact becomes greater with time. I have no idea what exactly is impacting you but I bet it's part of your lifestyle. I think buddists and pig farmers have shown us you can love what you do if you want.
I wouldn't recommend using food as a reward. It sets food on a pedestal it does not deserve. Food is calories and nutrition that enables you to perform your best; glorifying it as a reward for accomplishment may set you up for failure down the road.
I really like it's OO, it's regular and explicit. _ conventions are flexible for rapid development yet interfaces can still be hardened if required. You can do all sorts of stuff with decorators and Meta classes that you might do in macros in other languages but these are much more readable and predictable. The package system is simple and effective.
In fact while testing mrsync to synchronize search indexes among prod servers they overloaded their switches cpu and took down the site for a few minutes.