1. Start NOW
Don’t wait to start. Start on the very day that you decide to. You don’t have to wait for the first of the month, for the kids to go back to school or for MONDAY. You can start today. 
2. Start SLOWLY
Your body will need time to adapt to exercise again so start slowly with lower weight, reps or sets than you have been accustomed to. If you are a seasoned campaigner in the gym it won’t take you long to get that conditioning back but just give yourself a little time. You will know when your conditioning and fitness have returned to normal.
3. Start SIMPLE
Use closed chain exercises and machine based weights to help you get back the neuromuscular elements required to progress to more advanced, open chain and unstable movements.
4. Set GOALS
I’m not talking about some nonsensical New Year’s Resolution. I’m talking about something specific. Treat yourself like an athlete. You don’t have to be one to think like one. Choose a goal and tailor your training to meet that goal. 
5. Make every change LONG TERM.
Ask yourself the following questions regarding every change you are considering to make to your lifestyle:
a.Can I maintain this for a day?
b.Can I maintain this for a week?
c.Can I maintain this for a month?
d.Can I maintain this for a year?
e.Can I maintain this for the rest of my life?
It sounds pedantic but ask yourself these questions in this order to emphasise the gravity of making a serious change. If you can’t commit to a long term change then you may be wasting your time with this goal or you may need to modify it slightly to make it work.
6. Think BIG
Think BIG to make the most effective changes. Consider the changes to your lifestyle that will make the most difference for the least effort. For health focus on the big 3: smoking, alcohol and exercise. For fitness focus on: progression, variation and consistency. For strength focus on: progression, technique and functionality.
Include others in your lifestyle plans and changes particularly if your change has a universal benefit like resistance training. Including others will make your training more enjoyable, contribute to the health of your friends and family and give you a tremendous psychological and emotional boost.
Remember that at the end of the day you are doing this for YOU. Creating a better version of yourself will help, inspire and create a great role model for others but you need to want to do it for YOURSELF because no-one will call you if you hit the snooze button, no-one will know that you didn’t reach your goal except for you and no-one is a greater critic or supporter of you than yourself.
Create objective measures and don’t cheat yourself or lie to yourself. Create a way to regularly validate your progress or regression. If you don’t do this you will have two problems. One is that if you are successful you will have no way of knowing exactly how far you have come. The second is if you regress you will have no way of assessing this to find out why you regressed so you can make the appropriate changes and try again.
10. Read Step no. 1 again and GO!