I will keep those first things first in my life, every day by choosing to think and act in accordance with reason, purpose and SELF-ESTEEM.
Do you feel that you deserve to be happy?
Do you feel guilty about wanting to be happy?
If you need to ponder those things, in any way, shape or form, then your self-esteem is not where it should be.
Of course, if you do not value REASON as an ultimate value, then your lack of self-esteem may in fact be warranted, because you recognize, at least subconsciously that you are avoiding your responsibility to think and act rationally and as a result you have mixed feelings about yourself.
On the one hand, you may actually gravitate towards feeling like a victim of circumstances beyond your control, because you are not comfortable with facing the reality of your own responsibility for your situation.
This may seem harsh to some but the inevitable result of not clearly and rationally choosing and defining your own values is perennial self-doubt i.e. low self-esteem.
A lot of pop psychology admonishes you to love yourself and use positive affirmations, and while these may have some benefit, they lack the underlying prerequisites of REASON and PURPOSE that are the foundation of self-esteem and like any structure built without a proper foundation, it will surely crumble at the first true challenge.
As a rational human being, which it is your choice to be, you will realize that your highest moral purpose is your own happiness. Note that I am NOT talking about hedonistic pleasure or any false value that would be obtained at someone else's expense. Neither of these have anything to do with true happiness.
Armed with this certainty of purpose and the self-esteem that helps you to be secure that you deserve to be happy, you will be optimally aligned to achieve your true potential to be the HERO OF YOUR OWN LIFE.