Find and choose a proven strength training program. There are many, but probably the most popular (and time proven) to get started would be literally any beginners 5x5 program. Learn how to perform the basic compound barbell lifts and aim to develop mastery in them. Those movements are the:
-Barbell Bench Press
-Standing Barbell Overhead Press
Over time, look into adding some conditioning 1-2 days per week. Some great methods are sled pushing/pulling, sprinting, hill sprinting, etcetera.
Eat a balanced diet consisting of whole foods 3 times per day. Try to get away from processed foods entirely and your food choices should be: meat, vegetables, fruit, oats, rice potatoes, etcetera. I am a big fan of this diet and it is how I eat: https://www.t-nation.com/diet-fat-loss/simple-diet
Sleep. Get at least 8 hours of sleep every night. Check out from bullshit and stress in your life.
That is really it my friend. A great quote by author/lifter Jim Wendler that I truly think sums up what it means to really make a change in yourself is:
"Habits require discipline, not motivation. Motivation drains you and is empty. Discipline and habits always work."
Some great resources to read and Google search are:
-Bill Starr, 5x5
-Starting Strength, by Mark Rippetoe
-5/3/1, by Jim Wendler
-Dinosaur Training, by Brooks Kubik