If you are like most people around you, you want to have a healthier body. You likely want less size around your waist but more in your muscles. Yet, where and when do you start? Right now, right here. Stop overthinking and complicating what you are going to do and just get to it with the following steps.
The first thing you have to do is change your outlook and attitude. Do you feel like you weight too much? Exercising and dieting to lose weight is a neverending battle. Instead, set a specific tangible goal to focus on instead. Losing x number of pounds works, as long as x is specific number and not tied to an event or deadline. Better yet is to stay you want to be able to deadlift x number of pounds or walk/run a 5k.
Once you set your intention, see your doctor. Any credible exercise article online or in print will advise you to see your physician prior to starting an exercise regimen. This isn't just so they don't get sued. You want a check-up with your medical professional so that you have clearance to do certain activities. Your doctor will also have a wealth of knowledge and information to share with you about your goal, likely including local resources and options you never knew about on your own.
Clean out your cabinets, fridge and freezer. You might have a lot of food to donate to a local pantry or friends, but it needs to be done. Restock everything with healthy choices. You'll still likely eat out often, but your kitchen is no longer going to feel like the appropriate place for junk food.
Record yourself before your journey. Do a serious weigh-in, measure yourself and get pictures. You want a before and after picture set to hang on the wall after you are done, preferably alongside a ribbon, certificate or even eventual trophy after your 5k or other event.
Listen carefully to how others around you respond when you tell them about your goal. Many will not really care, or even rain down on your goal. Don't get defensive. Just tune them out and save your energy for training and exercising. Keep an ear out though for those that might cheer you on. You'll need a support group. You might even find a workout partner or group along the way.
Now, after all that, are you ready to actually start exercising. Get online or find a good book about your goal and read it thoroughly. Just about any fitness goal you can imagine already has a tremendous body of knowledge regarding it, so finding a fitness plan should not take long. Just remember to be conservative and start off in the smallest pieces you can manage. It might seem overly easy and even boring at first, but you want to get in a steady habit of training. Within three weeks, you'll likely head out and train without even thinking about it.
Keep that before picture up where you alone see it often, with a blank space for the after picture. You will fall of the wagon at times, but if you crafted the right wagon to start with, you'll get back on easily.