This is going to sound ridiculous, but I bought a child's plate (one with separated sections and about 25 cm in diameter).
The largest section is my veg, other two are protein and starch. If we are entertaining, I transfer that food to a regular plate, otherwise that is what I eat from.
Activity for me was easier after at least the first 6-8 weeks as it became routine.
I have a fitbit, and do my best to hit or exceed my goals every day.
Aside from that, my biggest help has been going it alone - if I wait for family members or friends to join me, nothing gets done.
I am very self conscious, so the gym is a difficult place for me, and solitary, so something like slimming world terrifies me.
My way is a little unconvenational, but it has been working.