When I wanted to lose weight I noticed it was the little things that made the difference.

Use the stairs not the lift if you can.

If you feel hungry have a drink of water instead because you often mistake hunger for being thirsty and..........

I replaced all the naughty stuff like crisps with nuts and dried fruit and took my two personal trainers out for walkies as often as I could

P.S. I would also sit on your brother until he learns to keep his smart*** remarks to himself