To be successful on your fitness journey you must have motivation. Motivation is what drives you forward toward your goal and motivation is what gets you to cross the finish line. However, to achieve your goals you must have a lasting motivation.
Motivation comes from two places; pain or purpose. Most people begin their fitness journey because of a painful moment. They step on the scale, go to the doctor, try on a swim suit, see a picture of themselves and see or hear something that makes them want to change the way they look or their health with a sense of urgency. This is not a bad way to start your journey, but you will fail if you depend on pain as your only source of motivation.
Here is an example; person A sees they have gained 50 lbs and decides it needs to change because they have never been that heavy before. Person A goes to the gym and starts eating a little healthier and loses 10 lbs in the first month. Person A is now feeling much more confident and pleased with the success they are seeing so the "pain" diminishes and the urgency along with it. Inevitably the weight loss slows as a reward meal is taken and exercise days get shorter and less often. Eventually all progress is lost and the weight begins to come back. As pain subsides the motivation disappears.
I have seen this process hundreds of times over the 15 years I have been helping clients reach their goals. The only way to succeed is to find your purpose. What does that look like? It is not based on sacrifice but on giving yourself more and valuing yourself more. It is not cutting bad food out, but choosing to add foods to improve your quality of life and health. Choose foods to add that give you sustained energy, help you sleep, and manage stress better. Motivation based on purpose has no end line to cross. It is letting go of habits that are killing you and replacing them with habits you are going to enjoy for the rest of your life.
If you need help applying this to you personally I would love to help you. Reaching your fitness goals should be a rewarding time of personal growth, marked by a long path of successful milestones. Yes it is going to be a challenge, but it will be a challenge you will succeed at!