This is a good question and I'll attempt to answer it from two angles. First, from the employer's angle.

You must understand that employees are very important to the success of any business endeavour. It's their contribution that brings collective success at the end of the business day, year, whatever you call it. There are certain things you have to do to keep them motivated.

First, you should be able to let them know that their efforts are not going without notice. Let them know how they've performed in their given tasks as often as possible. It's not out of place to praise your employees from time to time. A praise report in the presence of other employees would go lengths to boost the morale of a worker and also provide impetus to work harder on the parts of other employees.

Also, you should give constructive criticism where necessary as this would challenge your employee(s) to put in more effort and produce better results.

Secondly, let your workers in on what's happening in the business. It would help if your workers know the situation of the company and that they can help. Employees are motivated when they feel they are actually seen as valuable as to know what's really going on rather than as instruments, pawns in the game.

Thirdly, provide room for employees to make contributions and suggestions. It would go a long way to motivate workers when they know that their inputs are considered valuable.

Many employers are not aware that some of the best suggestions can come from workers who may see things the way executives and managers may not.

Lastly, in this regard, provide incentives for your workers after certain milestones. This could be in form of promotion, holidays or cash. This shouldn't be too often though but just enough to know their efforts are appreciated.

All of these when done correctly would keep your workers motivated.

Then, on the part of the employee, to stay motivated requires some things to be done. Your mindset has to be properly tuned.

First, you've got to like your job and keep on the table the things that motivates you. There's bound to be those things in your job that brings you joy and those that do not. You want to focus on the things that keeps you motivated. Is it the thrill of meeting new customers, or the idea of working with a team? Let these things always be in your mind. It will help to keep you motivated.

Secondly, set goals for yourself and try to achieve them. It's known that goals are serious motivators. The reason why you may not feel motivated is probably because there are no goals to achieve. Even if the job is something that you repeat over and over again, setting new goals could help you stay motivated. Like, trying to best your previous record. Can you get it done faster? Can it be more accurate? These would motivate you into continuing the work.

Thirdly, improve on your relationship with other members of your team. Your work may become boring and unexciting when you isolate yourself from your colleagues. Get to know them some more and have some fun moments with them. It could go far towards keep you motivated. You could even decide to form some sort of club after work, so you always look to get your job done with the view of spending some time with your colleagues later.

Lastly, try and incorporate the things you enjoy into your work. Your work and personal life doesn't always have to be separate. You could meet your employer and ask that your work should reflect things you enjoy doing. Maybe you enjoy meeting new people or analysing samples, just let your employer know and he may help provide a better work schedule for you.

I hope this helps.