If a Buddhist believes lay life is not ideal for the practice, why does he or she continue? Usually in the evening, when I am about to retire, I commit myself to finding and entering into a residential Sangha permanently.

When morning rolls in, I fall back into my usual patterns like work, hobbies, social, etc.

Usually when I suffer, this emboldens me to seek the monastic life but usually doesn't last very long.

When I think about it, I feel like the monastic life is the only way to proceed yet I don't follow through with it. 

Speaking from a general point-of-view, if a Buddhist knows that the lay life is not ideal, what barriers (overt and inconspicuous) are preventing them from seeking and living the monastical life. How can they be overcomed ?
Why does he or she continue?


Because of clinging. Clinging to family, clinging to lovers, clinging to property, clinging to comforts, clinging to all kinds of sensual pleasures which the monastic life wouldn't have.


  How to overcome it?


You have to develop Nekkhamma Sankappa of the noble 8 fold path.  Take a timeout  to think about what you've really been trying to do every day, your whole life. Being yourself subjected to birth, sickness, aging, death etc. which cause suffering, you are trying to attain satisfaction by chasing after other things which are also subjected to birth, sickness, aging and death.  This is called the ignoble search. Think of the absurdness of doing the same thing over and over again, when it can never give you the intended outcome. Pay careful and wise attention to the signs of Anicca, Dukkha, Anatta in life. What made prince Siddhartha decide to leave the lay life? Seeing an old man, a sick man, a dead body, a hermit. We see the same things too. But we rarely pay wise attention. We rarely think that we are also subjected to the same misery. Even if we do think that, it would just be a passing thought. It wouldn't be strong enough to break the bonds of lay life. It wasn't a passing thought for prince Siddhartha. He thought about what he saw even after returning to the palace. He cultivated his mind with Nekkhamma thoughts, which eventually became strong enough to make him decide to leave the lay life to do the noble search. i.e. to seek the unborn, unaging and the deathless element.