I lost a substantial amount of weight (6 stone) and have kept it off for almost a decade.
People yo-yo, losing weight, then they go back to over eating and put it back on, and tell themselves excuses (like I used to) and have unhealthy thinking trends like 'I need a treat/it's Christmas/I had a bad day' to let themselves overeat.
I've often heard overweight friends/family say 'I couldn't possibly give up cheese/cake/crisps, life is too short!' But the irony is they are at risk of shortening their lives being so unhealthy. You don't have to go totally without, just be mindful and not eat those things every day. They have no balance.
A lot of people have lost sight of portion control too and are totally uneducated when it comes to calories and nutrition.
There's no special secret to weight loss or maintaining a weight, you just need healthy habits, stop the excuses and take responsibility for your wellbeing.