How can an individual develop self-worth when feeling like they are fulfilling no purpose in life?

When feeling like I am fulfilling no purpose in life, simply do just two things:

1. Understand what is the purpose of life, and
2. Try and pursue that purpose of life.

The self-worth shall then develop automatically.
Param Pujya Dada Bhagwan, the Enlightened being, suggests:
There are two main purposes of human life:

1. Helping others,
2. Knowing the real Self (Self Realization).

1. Help Others:

“Life is meant for practicing benevolence and serving others. The deepest science behind this is that when one uses his mind, speech and body for serving others, he will have everything”, says Param Pujya Dadashri, “You will not encounter any obstacles in your life if you help others in any way. When a person begins to serve with only half the understanding, he gets a contrary result; and therefore, he loses faith in serving others. If one were to serve people in this life, he will reap the rewards of his service in the next two or three lifetimes - this is the very science!”
Therefore, have an obliging nature and offer help to people. More important than a person's external action to help others, is his internal intent to help. This intention should always be present within us. And the intent ought to be sincere and should be flowing from the heart; only then it is fruitful. The service to people is considered real when done without any greed or any expectation of fame or recognition.

We can serve people by giving food, medicine or even knowledge that one may be in need of, in order to help reduce their misery. Nevertheless, the biggest help that we can do to others is - to not hurt anyone, in the slightest degree, through our words, our actions, and not even in our thoughts!

Happiness begins from the moment we have an intent to help others. And when our very purpose of life becomes that of helping others, we eventually get onto the path of spiritual progress, as Nature, in turn, helps arrange our meeting with Gnani, the Enlightened One, some day!!

2. Attain Self-Realization:

Our very Self is an abode of infinite bliss; yet we keep hunting for happiness in the material things that are available on this planet. Param Pujya Dadashri says, “If one realizes his own Self, then he himself is an Absolute Supreme Soul (Parmatma).” What more self-worth could one ask for?

So, knowing our real Self is indeed the sole purpose in life! But how do we get there??

Just as we need a goldsmith to separate pure gold from the impurities of the other metals, similarly, we need a Gnani Purush to separate our pure Self from the impurities of the non-self (body, mind, ego, intellect, attachment, hatred, anger, etc). With the divine power of Gnani Purush, it is possible to attain Self Realization effortlessly!!!
The law of Nature is such that when one has a pure sincere intent to get liberated, one will surely happen to meet the Gnani, who can liberate him. Presently, we are fortunate to have between us Pujya Deepakbhai, with whose grace, one can realize the real Self and experience their Soul!!!
So, to conclude,

• If you have not met a Gnani, then live life in such a way, that you hurt no one and you be of help to others.
• And if you happen to meet Gnani, then attain Self-Realization and remaining in Gnani’s company, fulfil your ultimate goal of liberation. When you do so, your purpose in life will be accomplished and all your puzzles will be solved!