I've made several changes in my life that I feel contribute to my loss. I don't know which changes have the most effect, but like anything I think it's a little bit of all of them.
First up, Eat real food, not too much, mostly plants. The book "In Defense of Food" changed my life. It's not a diet at all, but guidelines to how to eat better for yourself and the environment. I feel this has had the most impact on my weight loss. I eat way more fruits and vegetables now but less food overall. I try (it's damn hard) to stop eating when I'm full.
I also go to the gym every day. I don't have a in-depth program. I just have day 1 and day 2. Day 1 is 25-30 minutes of cardio and some simple weight training. I typically hit each major muscle set with one set of reps. Day two rests my weight training -- I do 40-45 minutes of cardio. I should also clarify that I don't hit the gym every day; I don't always go if I'm doing some other physical activity that day.
I've been working from home since mid-January. I use the gym in my building at lunch. Again, I do it every day. Commuting and lack of showers in my office were a huge mental barrier for me doing this in the past.
I've also been reliably and visually recording my weight. Every Monday I weigh in when I get up. I put my weight into a google spread sheet and it draws a graph for me. Seeing my progress has been a great reinforcement.
On top of the spreadsheet, I said in January that I want to be 190lbs by May 1 (I'm a pound off track right now). I used the spreadsheet to track where my progress should be. I purposely set my goals for roughly a pound a week. I was able to do a quick formula to show me where I should be every week. This allowed my to check my progress in bite sized pieces.
Good luck!