If motivating others were easy, everyone would do it. You can’t just read about a few techniques and implement them, expecting major changes to happen. It takes practice like anything else worthwhile.
Motivating others requires them to be willing. If someone is hard-set in not doing something, there will be little you can do to change that. You may be able to force someone, i.e., if you are a manager, etc. However, that is not the same as motivating them. If you were to leave the company, they would revert to their previous behavior.
Realize that trying a technique only when the mood strikes is not going to produce results. You must be dedicated to trying them out and continue doing so until you see results. You also need to determine when something isn’t working after several tries and seek an alternative approach. Unfortunately, there is no magic number as to when to make that determination.
Motivating others is about aligning their goals with yours. This alignment could require some compromises in the process. For instance, if you are trying to get one of your colleagues to do something, you need to listen to them if they legitimately say they have too much other work. You can offer to have someone else on your team take up some of the extra work, or you could even do it yourself under certain circumstances.
You can’t approach motivation as entirely academic. In other words, if you read about something and try to implement it, you think it should work. If it doesn’t, you may blame the people you are trying to motivate and believe there is something wrong with them. However, some people may be going through stressful situations and so are not able to focus on their jobs or even their personal life. You need to have compassion for them and factor in human emotions that may be at play. If you haven't done Mental Health First Aid Training, this might be a great opportunity to learn some new skills.
If motivating others isn’t working, you should try to find out why. It may be something you are doing that needs change. For instance, are you practicing what you preach? If you are telling everyone that they must work on weekends but are unwilling to work yourself, then you will experience resistance from your team. You will have much better results if you are on the front lines with your troops.
Motivation is more about communication than barking orders. It is about getting people to recognize the importance of the work or task at hand. You must allow them to take the initiative and own the problem and their solution.