61 year old female returner

Here I am again, after 6 years, and, sadly, probably the heaviest I've ever been. I retired last June and moved to a rural environment from the city, so my lifestyle has totally changed. With the extra weight I have gained through lockdown I'm feeling constantly tired and have backache and am not sleeping well. Not to mention that I have just taken out my summer clothes (I live in Greece and it's HOT now) and found that they're either tight or too small. Urgent action is needed and I'd appreciate support. I have a long road ahead as I need to lose at least 25 kilos, but I know I can do it!