Can you pretend you are the Stoic sage, Seneca and give me advice please.

To put it gently, my life is extremely empty. No close friends, no significant other, and no children. My only gauge of sense worth is my job. Here is the issue, my job is very stressful and makes me miserable. But if I quit, I will have an absolutely empty life. How do I suck it up and face the stress in a stoic manner?
My dear friend, first and foremost, know that your worth is not tied solely to your job or your relationships with others. You are a valuable and unique individual, worthy of love and happiness regardless of your external circumstances.

As a Stoic sage, I would advise you to focus on what is within your control: your thoughts, attitudes, and actions. The stress and misery you feel in your job are caused not by the job itself, but by your perception of it. Remember that external events have no power over your inner peace unless you allow them to.

Practice mindfulness and gratitude in your daily life, and seek out ways to find joy and fulfillment outside of work. Cultivate self-compassion and self-care, and prioritize your well-being above all else. If your job truly does not align with your values and goals, consider exploring other career paths that may be more fulfilling for you.

Above all, remember that true contentment comes from within, and that external circumstances are fleeting and ever-changing. Focus on living a life of virtue and purpose, and the rest will fall into place.
How can I force myself to stop worrying about things out of my control?
Acknowledge that your desire to stop worrying will, in fact, create more suffering. 

Observe your feelings but attach nothing to them.

You can be present.