How can I lose weight by not going to the gym? What can I do?

Exercise at home. .. Or outside. Housework and yard work can be turned into exercise if you get your heart rate up. Or go for walks. Exercise will help, but to be successful at losing weight it's important to change eating habits too, like cutting down on portion sizes, eating regularly throughout the day, and eating only until satisfied. Eat foods that will fill you up without a lot of calories, like whole grains.
Same. No gym if self motivated. Do a cardio stretch and strenght routine I just did 10 push up in my office, and10 squads in less than 1 min. Do an exercise that you like otherwise you won't do it. Eat fruit lots of fruit. Sleep well every day and meditate at least 5-10 min per day.
Exercise at home. If you don't want to go to the gym-try exercising at home. There are plenty of at home exercise routines you can do. Or go for a walk/run/bike ride outside. Watch your diet. You need to burn more calories than you consume. Cut junk food out of your diet and eat healthy. Pay attention to liquids-soda and alcohol can contain a lot of calories. Don't overeat and make healthy choices.