For The Past Several Years I Have Been Inactive (exercising)

For the past several years I have been inactive (exercising) due to depression of financial situations. I have gained weight. I have noticed retention in my legs. My left leg around the chin is bigger than my right leg. If I were to start exercising will that help my situation. My Dr is aware of the swelling (6mo ago) but it wasn't that bad. Due to my husbands health issues and financial I haven't gone to the doctor. I want to try to resolve this on my own. Please advise. Thank you