When starting a diet to lose weight don't start an exercise program. Just do what you are already doing. Concentrate on the diet plan you have chosen. If you must exercise start with walking 5 minutes out and 5 minutes back.
Then walk 8 minutes after each of the 3 main meals each day.
Finally minimum walking 20 minutes a day. 40 minutes is great. Lift light weight 2-3 times a week if able.
To maintain weight loss: Walk at least 20 minutes a day for health effect.
Guidelines below with evidence
Critique of Exercise Studies presented at OMA meeting in Washington DC 2015
No random control trial for exercise.
Poor adherence in studies.
When adherence was good, exercise was good,
when adherence was poor, exercise results not good.