Maybe. I've actually implemented a rather complex set of rules to maintain my weight and it has been working so far. I keep a rough estimate of the calorie intake every day and try to keep it within reasonable bounds. I do make exceptions (hey I still love eating 2 pounds of steak with 3 pints of beer), but those days are followed by heavy dieting days to bring the calorie balance back. I also have a high-watermark/low-watermark system for my weight, so in case it runs away (like during holidays or trips), I am still 1.5-2.5 weeks away from reaching my normal weight.
I'll level with you: the easiest part for me so far was the initial weight loss. I got down to 15lbs less than I am now and it was much easier than it has been since. It's like my body adjusted and got much more conservative but it took a year or two. Maybe that won't be true in your case, but give it time before you make an assessment about the difficulty.
Trust me, it's too soon to say what you're saying. Source: lost >150lbs and kept it off for the past decade.