I’d recommend that if you are in this for the long haul then the sensible approach is the best.
Start with small manageable changes, the two easiest ones are drink more water and always have a healthy nutritious breakfast.
Remove yourself from a mentality of good and bad foods, food is food! There is only everyday and sometimes foods. If you fancy a bit of cake have it just don’t eat the whole damn thing(unless it’s an individual serve of course).
Good fats- nuts, seeds, avocado, oils are not the enemy but you do need to be mindful of portion size as they are calorie dense. Allergies notwithstanding nuts and seeds are a fantastic snack, and don’t require refrigeration.
See if your GP can refer you to a dietician. I’m not sure where you are and if self referral is an option available where you are.
In terms of exercise cycling, swimming and walking are my default recommendations. With the pandemic, the swimming will need to wait. The reason I suggest the above is the low impact nature of them on your joints. Running will burn more calories but if you are obese at present your joints will not thank you for it. Although, in saying that many believe that the overall picture of weight loss negates the initial impact of running with the excess weight.
You can start to increase muscle strength by doing squats at home, but look up the correct technique online. Bottles of water or tinned food in each hand and you have yourself free weights.You can do arm exercises with them.
One of my DC was complaining about not having looked after themselves today. In the warmer weather at bedtime they realised how little they had drunk. Their wellbeing goal for tomorrow(well today now) is to drink the age appropriate amount of water for the day.
Oh and if you feel at any point you have fallen off the wagon all is not lost, you have not undone all your hard work. You have merely had a temporary setback. We are all human we don’t need to get things right 100% of the time we just need to keep heading in the right direction.