As someone who lost and kept off half their body weight: I very much support the "eat the same thing all the time" meal plan. A lot of people who get to be as big as I was are food addicts, so the less time you spend thinking about food, the better. The less time you spend in a grocery store looking at food, the better. The less food you have hanging out in your fridge, the better.

OP literally said he gets rundown and depressed by his healthy eating strategy.

He needs to learn to cook more things.