There are lots of different opinions here as to what form of exercise you should do, but as someone who lost a significant amount of weight a few years ago (124kg -> 85kg) there are two things that really worked for me:
1) Booking an exercise class rather than simply going to a gym to workout alone created an appointment that I felt I should not miss. For me that made it more likely I would go than make an excuse not to. When I started it was an appointment with a personal trainer, and as I got fitter I joined a CrossFit gym and booked into sessions that started at a certain time. In both cases, the fact that I had a booking at a certain time carried me through on days when I really wanted to miss it. Training with someone else might provide the same encouragement - arranging to meet up with someone else to train at a certain time & place would mean even if I didn't want to, I would go because I wouldn't want to let them down.
2) However much you think exercise is the key to weight loss, it really isn't. It helps, but your diet is the most important factor. Start counting calories of everything you eat / drink. It's a pain to have to weigh everything and work it out, but there are apps that help, and without this knowledge it is so much harder. Counting calories will educate as well as inform, and you'll be surprised how soon you start wanting to make better decisions on what you eat.
As for what exercise, it doesn't really matter what form of exercise it is as long as it's something you enjoy. It won't matter how motivated you think you are, unless it's something you enjoy you'll struggle to develop it into a routine you can take forward longterm.