Simple. You like it.
What do I mean?
Tolerating a diet's not good enough. If you're only tolerating your new lifestyle you're certainly not likely to keep living it.
Food wise - you can't be regularly battling hunger, it can't be making you feel unwell and your life has to be "normal" meaning you should be able to include food for comfort, food for celebration, with no forbidden foods.
Fitness wise - you can't be running out of time, running out of energy, hurting yourself or hating it.
Ultimately you're aiming for a lifestyle where you can't happily eat any less and you can't happily exercise any more.
Sure we can all improve our lifestyles but to use an extreme example, do you really think you can be a tee-totaling vegan, shut-in, marathon runner forever?
If you can't happily eat less, you're not going to eat less. If you can't happily exercise more, you're not going to exercise more.
Your goal should be your personal best recognizing that the best lifestyle you can enjoy and the best lifestyle that you can tolerate are two very different things.
Is there any other aspect of your life about which you're striving to be "ideal"?