Lingering within every beating heart is one question we all seek an
answer to and basically it is about the reason for our existence as
individuals. It's often asked in various forms from "why am I
existing?", "what is my calling?" to "what is my purpose in life?"
amongst others.

Let me first point out that the pursuit of meaning from a perspective
outside of creation is futile and baseless and this is what I mean;
that it only makes sense to ask what is the reason for my existence
when you acknowledge that your existence is as a result of intent and
not mere coincidence.

Scientists claim that everything in life is as a result of time,
chance and matter and thanks to evolution, there resulted every other
known life forms from simple to complex. The implication of this is
that there's literally no intention or reason for life seeing that it
all resulted from a big bang of coincidence. Where there isn't a
reason for life in the first place, then there's no point asking
"what's the purpose for my existence?" because the answer will simply
be nothing! You exist for nothing.

     However, from the Christian perspective, everything there is, is
said to be created meaning that our existence is intentional. Now the
only way to know the intention of a thing is to ask the one who
created it in the first place. With this, when we ask why we exists,
there's a reference point we can all fall to; God. Thus, the quest for
meaning only makes sense within the perspective of creation alone
because there's intent and where there's intent, we find reason.
Having established this, let me move on to clarify a popular
misconception in the quest of finding meaning. Though often used
interchangeably, your calling is quite different from your purpose.

The bible says "All things work together for the good of those who
love God and are CALLED according to His PURPOSE." This shows us that
a calling is not the same thing as purpose. From the above text, we
see that we are called into purpose meaning that your calling is what
leads you to purpose while purpose is simply the reason for your
existence. Let's look at it this way. If I say to you, come! You're
most likely to say "here I am, what can I do for you?" Then I go on to
say "I'd want you to look after my belongings for me while I attend to
something urgent." What I have done is that I have called you
according to my purpose. The reason I called you is so that you may
know what I would have you do for me. Now I already know what I want
you to do for me before I called you and so my calling you is to bring
your attention to what I'd have you do for me. This is how it works.
God already has what He'd have us do for Him ie (our purpose) but
until He brings it to our attention (by calling us), we remain unaware
of it.

Take Moses for example, his calling was the burning bush, for that was
how God got his attention but his purpose was to lead the Isrealites
out of slavery in Egypt and into the promise land.
From what we've said so far about a calling, it is important to note
that it is God who calls us and as such, we have very little or
nothing to do about the call. He calls as He wills. But then we can
pray and ask Him for our purpose, showing our desire and willingness
to walk in it and He'll call and reveal it to us, for the bible says
"Blessed are those who hunger and thirst, for they shall be filled."
meaning that if we earnestly desire to walk according to His purpose
for us, He will reveal it to us.

I guess this answers the question "How do I discover my purpose?". You
can only discover your purpose by asking He who made you to reveal it
unto you.

However, there are certain things that gives us an idea of what our
purpose is and as good as they may be/seem, they are just clues that
should ultimately lead us back to God.
One of these is known as propensity. A propensity is simply that which
you naturally enjoy doing with less stress yet yielding maximum result
at it. You don't force it, it just flows from within you. It's quite
different from acquiring a skill, you're born with it. You know that
situation when you see someone excel in a thing and you just exclaim
Wow! He is born for this!? That's an idea to what propensity is all
about.

When you can identify your propensity, it will give you a clue as to
what your purpose in life is.
   Another is Passion. What are you passionate about? What makes you
uncomfortable? What brings out the activist in you? This too when
identified, provides you with a clue as to what your purpose in life
is.
Yet another is pain/experiences. What is that thing that hurt you so
bad that you can't stand seeing someone else go through it? What is
that phase of life you've gone through that makes you say "no one else
has to go through this"? This too is another pointer leading unto
ultimate purpose.

Let me point out that in the search of purpose, we need to realize
that it's never about us. It is always for the benefit of others. Look
at the lives of great men who stand out through the ages, from Moses,
Ghandi, Mother Theresa, Mary Slessor, to Mandela, Martin Luther King,
to the apostles of old and even down to Jesus Himself, they lived
their lives for the sake of others. So it is pertinent you put it at
the back of your mind that whatever purpose God has for you, it is
ultimately for the sake of others.
Lastly, spiritual giftings also gives us a clue as to what our purpose
is in life. Be it the gift of teaching, prophecy, healing, helps, etc.
When you discover the manifestation of one or more of the gifts of God
upon you, then it should serve as a pointer towards the path of
purpose.

Whichever of the above clue finders you decide to implore, look
closely, there should be a thin line that runs through each of them
and that is the closest you can get to finding out your purpose in
life; but remember, it should lead you back to the feet of the master
where only true purpose can be revealed.
I hope I have been able to answer your question on "discovering your
purpose". Because the topic is one that entails a lot, I cannot say I
have exhaustively put this discussion to rest and so, I would like to
recommend "Purpose Driven Life" by Rick Warren and "The Making of a
Chosen Vessel" by Bishop Bob Alonge if you need more insight to this
topic.