It's OK not to take on every assignment.
It happens to the most well-intentioned among us. You're asked to do something at work outside of your normal duties and you willingly agree. You do a good job and the following week you are asked by the same person to do something else. This continues for a long time and you eventually begin to feel overburdened and as if you're being taken advantage of.
You're probably asking how you got yourself in this position and how to get out of it. The first step is recognition. If you feel you've fallen into this role, you can take action to remove yourself from it. No one wants to feel that they've lost control of their work balance, and this can quickly happen when you are being walked over.
Focus on you. If you've landed in this position, it may be due to insecurity. Are you afraid to disappoint others? That may be why you are taking on every new task given to you. You need to learn to value your contributions and time, which will allow you to do what you need to do to be successful without compromising your priorities, utmost of which should be caring for yourself.
Ask for help. When you are constantly giving to others, you're probably not asking for much help. That can be damaging to your well-being as well as from a time perspective. Asking for help does not exhibit weakness; rather, it shows that you acknowledge you don't know the answer to everything and it's okay to ask for assistance. You're not supposed to know all the answers! This also sends the signal to your colleagues that you are not afraid to ask for help, and you will not be the one doing all the grunt work.
Learn to say no. This is a tough one, but it's an essential skill in the workplace. Those who set up boundaries tend to have a more positive experience on the job. Contrary to what you may think, saying "yes" to every request can give your co-workers a negative impression. They may see that as an inability on your part to prioritize overall and maintain a balance. It's much better to be honest up front when you do not have time for something. If you wait until a day or two before a deadline to tell someone you won't have time to complete something instead of saying "no" at the outset, you will also damage your reputation. If this is hard for you to do, start by offering to do smaller tasks that take very little time, say five to ten minutes, and go from there.
Evaluate your to-do list. Learn to think critically about your to-do list. What is absolutely essential and must be done today? What can wait until tomorrow? With constant access to email, we automatically think that every message warrants a response as soon as possible. However, continuously asking yourself the question "Does this really need to be done right now?" may yield surprising results and give you back a lot of your free time.
Cut back on your hours. If you're always working overtime and feel that you need to be the first one in the office and last one out, ditch that mentality. In most cases, you'll gain more respect for completing your work within your workday (with some exceptions of course), and if you don't, there's likely something wrong with your boss, management or company culture. If there are obstacles stopping you from getting your work done within normal work hours, think about how to slash them. Is there a barrage of meetings each day or people who are constantly coming to gossip with you and interrupt your work? These are two things you can skip or cut out by making the decision and sticking with it.
In order to avoid the office doormat label, you first need to recognize your self-worth. Once you accept that your time is valuable and you deserve respect, you can begin to take back your time and energy and put it into your core work tasks and personal time in order to do things that matter to you. Don't let people take advantage of your kindness and willingness to give of your knowledge and time. It's not worth the long-term risk to your health or your professional reputation.