Hi,
I understand your concern, and you also realise that due to less activity your weight is gaining but to be fit one need to follow a balanced diet and exercise, there is no other way. Include more vegetables, fruits and complex carbohydrates and good quality protein in your daily diet. Drink water 3 litre per day and have a sound sleep about 6-7 hours.
Next Steps
If you want you can chat directly with me through this practo app for further discussion.
Health Tips
Try to do exercise, atleast for 30 minutes, it will increase your activity level.