I've been there. I lost 85 pounds, got off the couch, and have maintained my loss for over a year thus far.
It sounds to me like you have "on/off" syndrome. You either take on too much at once and burn out, or you don't do anything.
All the things you have to do lose weight and get in shape are the things you have to do to keep the weight off and stay fit. So instead of thinking of your lifestyle changes as what you do to lose weight, think of your choices, behaviors and habits as things you do to promote health and well-being, things you will do every day for the rest of your life.
If you burn out when going out full throttle, try making changes one small change at a time, incorporating new habits until they become the status quo, and then adding new ones.
For example, don't overhaul your diet and start an all-out exercise program all at once. Start with breakfast. This week. Today. And make a goal that you will eat a proper, health-promoting breakfast every day. That's all. Just do it one day at a time. (Or whatever other goal you choose.)
When that becomes easy, add something else. Say, you vow to do an at-home circuit of 1 round of pushups, squats, and pullups 3 days on, 1 day off. Then 2 rounds. Then 3......
The idea is to make each change sustainable, until you are living the life you envision for yourself.
Better to be successful at incorporating small changes than to fail at sustaining Big Efforts.
Anyway, as someone who failed any number of diets and programs, that worked for me. I wish you many small successes...:-)