#1
I've honestly never been in your situation so I'm not entirely sure how to respond. I would be able to give better general advise if I knew what you were capable of. An example of what I mean: are you able to run, or can you only run at a brisk pace? How about biking? Are push ups or burp-ees a possibility? How active are you currently?

Beyond that I can only give my two cents on a healthy diet. The key I found was trying to eliminate excess water weight. You don't need a drastic dietary change; it can be done by simply cutting down sugars and salt. I know for me a simple starting change was not eating sugary cereals anymore, and committing to drinking only water (and black coffee) and LOTS of it! It helps fill you up before meals so you eat less, and you always feel better fully hydrated.

So besides maybe a bit more background information I can only say two more things.
1) Regardless of what it is, you need to enjoy doing it for your mental health. Pick a sport or an athletic skill to work on!
2) Do NOT set a goal of "lose 50 pounds". It is far too vague to be motivating and therefore accomplish. If you want that to be your goal at the very least set a realistic time you expect to achieve it by, keeping in mind the average considered healthy weight loss is 2 lbs/week.