Your mindset is a huge element in you achieving successful training.
This is a tricky subject to clearly define as everyone is so different and responds to a wide variety of ways of thinking. Some find training fun and find it difficult to skip a session, others don't. This gives people a totally different jumping off point in where they need to be mentally to succeed.
However, there are a few elements that are true to everyone. They come easier to some than others, but I think everyone needs to work on them at some point.
Blaming, moaning and excuses have no place in this process. Mainly because they don't accomplish anything and will in no way make you fitter, faster or stronger. Those who take ownership look internally and not externally. By accepting that the actions you follow will shape your results, you will do what you can to fix a problem - this is how people get stuff done!
"I'm not getting fitter because I'm too busy. It's my bosses fault because they are giving me too much to do." (moaning/excuse/blaming)
While it may be true that your boss overworks you, blaming them and moaning about it doesn't decrease your workload and free up time to train.
Those with ownership will think along the lines of.
"I'm not making the time to train. I either need to scale back my goal, or adjust my schedule to make the time to train. I could do shorter, more intense workouts, join a gym closer to work, stay up later, wake up earlier etc etc"
Who is more likely to succeed?
Discipline is the willingness to do what needs to be done, even when you don't want to do it.
If you want to train more - train more.
If you want to sleep more - go to bed earlier.
If you want to learn how to do a pull up - practice your pull ups.
For some, its that simple. For others, they will need to scale it back into smaller more manageable chunks. Either way, you have to follow consistent actions to get results. That takes time and there will be resistance. The only way you break through that resistance, is to keep fighting at it.
Disciple provides structure - structure provides success.
Pay attention to what you are doing and why you are doing it. I honestly believe that people would put there phones away in the gym if they thought about why they were there in the first place. Do you go to train and progress to your goals or do you go to catch up on your friends holiday pictures or sharing every element of your workout with a motivational quote.
Approach the gym like its a gym, the weights as steps to your goals and your rest as time to recover and you will be leaps and bounds ahead of the average gym goer.