Here’s another way to look at this. Maybe it is not you who is asking the question, maybe it is life that is asking you "What sort of meaning are you going to give this life."

And You will not find the answer in some abstract philosophy because the meaning of life is not something vague but very real and concrete just like your life’s task. So If you wake up every day and respond to life by being responsible to your daily tasks and duties. Then You find profound meaning in Life. People have found immense meaning in responsibility.

All this is still a conjecture because we can never be sure about the ultimate meaning of life as humans are still not at the terminal point of evolution in the big game of the cosmos.

The ultimate meaning of life is beyond our comprehension and surpasses the finite intellectual capacities of humans. You have to make peace with the idea that humans are incapable to be sure about unconditional meaningfulness in rational terms.

Love enables us to see potential in the beloved person which is not yet actualized but yet ought to be actualized. No one can fully become aware of the very essence of another human being unless one loves the other. Driven by love one encourages the other to actualize the potential.

Love is as primary a phenomenon as sex. Sex is justified and even sanctified as soon as, but only as long as, It is a vehicle of love.

E Viktor Frankl’s logotherapy is a school of psychology that suggests that meaning in life is the primary motivation of life (Will to meaning).

According to Freudian psychoanalysis, Man wants pleasure (will to pleasure).

But Alderian psychology is based on the fact that Humans strive for superiority (Will to power). Also endorsed by Nietzsche.

Don't aim at success - the more you aim at it and make it a target, the more you are going to miss it. Success, like happiness, cannot be pursued

They are the byproduct of following a cause that is much greater than ourselves or the byproduct of following habits, processes, systems or routines. 

Instead, listen to what your conscience commands you to do and go on to carry it out to the best of your knowledge. 

Then you will live to see that in the long run - in the long run, I say! - success will follow you precisely because you had forgotten to think of it."

Pleasure or Happiness seems to be a bad compass for life. They're a side effect of a moral venture. But As an aim, they're only for toddlers or narcissists because when you’re suffering you’re gonna need something that is more robust than happiness to overcome the insurmountable obstacles. 

But An individual who is striving for meaning in life can overcome any obstacles, he is the most ready for an adventure like life. He who has a why to live can almost bear it anyhow. 

When you’re optimistic even in the face of the TRAGIC TRIAD and saying yes to life in spite of everything and learning how to turn life’s negative aspects into something positive or constructive then you know what it means to be Tragically Optimistic.

The Tragic Triad of Life consists of the following:

1)Pain

2)Guilt 

3)Death. 

Pain encourages us to turn human suffering into achievement and human accomplishment.

Guilt propels us to seize an opportunity to change ourselves for the better. 

Death being life’s most transitory moment teaches us to be more responsible with our time and be less vain in our pursuits. Life is defined by death, if we were immortal we would be less productive and vain in our pursuits. We would have been more dead than alive.

PS: You must understand that you can’t command yourself to be tragically optimistic.