The aim of making merit is to abandon sin and help you purify your mind. All defilements (Kilesa) which stay inside will cloud you mind.
How to have a powerful mind
Being aware of your emotions with mindfulness (Sati) will make your mind powerful and not cause anger (Dosa), greed (Lobha) and delusions (Moha).
Awareness of emotions raises your mind above any feelings. Just like building immunity inside yourself and improving your mental health. When you have mindfulness (Sati), concentration (Samāti) and wisdom (Pañña) you can live freely anywhere.
Meditation retreats will help you to see if you are cultivating greed inside you. You should not be greedy, stingy and selfish. You should do good deeds to others. By wishing others to feel happy from your meritorious actions. This is the root of goodness (Kusalamūla) that occurs in your mind.
Greed is a delusion that obsesses the mind with trivial things. It is unwholesome (Akusala) and impure (Kilesa). When you give up your time for doing good things, for example: giving (Dānā), observing religious precepts (Sīla) and mental development (Bhāvanā), these meritorious actions will improve your mind. We have 24 hours a day. As you are Buddhist do you have spare time to do these good things?
One fibre is not called thread. Many fibres spun will become a thread. Many threads woven together become cloth. Everything has its own process. You should not dwell on the past with sorrow and sadness. Do not worry about the future, because it’s not arrived yet! Live in the present, make the most of your time and you will be sublime.
Dhamma or the truth occurs and persists whether Buddhas exist in the world or not. The natural elements of life are non-lasting.
Mental formations (Sangkhārā) are non-permanent. Everything occurs, carries on and disappears. Because Dhamma follows the laws of nature.