Mentally Stuck

I feel like I have some mental barrier causing me from sticking to an eating plan/working out. Every time I see something sweet I feel like I HAVE to eat it, and find it incredibly difficult to stop. I am a 5’6” 235lb female and have been wanting to lose weight my whole life. I know what to do and what steps to take but find the mindset of it all so draining and exhausting. Any advice on where to go from here??