I started working out on my own about 9 years ago (no gym though - home made exercises).
I weighted 130kg before that (it slowly piled up over an 8 year period from when I was 13 years old - before that I was pretty 'average') and lost 46kg in 4 months.
Ever since then I meditate on a regular basis, and work out by going out for a jog (45 to 60 mins - depending how much I feel up to at the time) with additional 15 mins (up to 30) for some body exercises with dumbbells - this I do about 2 days in a row, with 1 day of rest, or just every other day (depends).
My knees had a tendency to complain at a time because of the jogging, but it settled down.
I usually stretch before jogging (and sometimes afterwards), so its usually not an issue.
I was thinking on taking up regular swimming in addition to my jogging because the former would have an easier time affecting the entire body - but memberships are a bit expensive right now, so I just exercise on my own.
I have no issues with motivation, and if I don't exercise at all for a period of time, I don't gain weight (I'm eating mostly 2 meals per day anyway which I split into 4 smaller ones, and it's mostly enough for me) - and getting back into working out, I like to ease into it more or less (if I see the need to - if not, then I just continue as I did before).