Discipline lacking... Need help!

Hi, I'm looking for a friend :-D

I'm a 27 y/o male yoyo dieter who can't stay motivated for more than 2 weeks without dunking a pork pie into a tub of mayonnaise.
I've managed to lose about 50lbs and now need to tone up, but I'm at risk of undoing it all with my ridiculous food binges.

For example, one day I'll happily run 5km eating fruit, fish and lifting weights (all at once - because I'm awesome), then spend the next day laying in bed pushing a whole battenburg cake into my face, with 10 bags of McCoys, 12 Strongbows, Fray Bentos pies and a domino's pizza for pudding. Sometimes I drink Marmite.
If there's anyone out there in a similar predicament, I'm happy to motivate in whatever way I can.
Been using this for a while but never had anyone to message - add me if you need/can give some encouragement!
Cheers!