When you have no assets that can generate passive income, think of yourself as your biggest asset. Generate the maximum possible income, have low expenses, with the minimum amount of time spent working.
Think of your time spent at work as an investment, i.e., try to get the most out of your work, not only in terms of cash-flow but also in terms of what you learn from it. I have realised that since I have assumed I will not work many more years and, therefore, I see my work as temporary, I take most advantage of it, I enrol in all kinds of interesting trainings, I put myself in challenging situations because I feel I can learn from them and I am not afraid of failure anymore, because I know I will also learn something from failure. I am also more confident to say what I think in meetings and more prone to apply to higher level positions. So, I guess I am better at work and this is due to the fact that I have decided I do not want to work forever and take it as a temporary situation. Ironic, right?
You are your biggest asset! At least until you have no other assets you can live from, think of yourself as an investment: you have to yield the maximum return to your shareholder, which is yourself!