What are the causes of a lack of self-confidence and trust in others, fear of new endeavors, hesitation in speaking, low morale, and increased heart rate?

What you are suffering from could be a physical illness, satanic whisperings (waswasah), or something else. We advise you to fear Allah and to safeguard the obligatory prayers and the morning and evening remembrances (adhkar), as well as those before sleeping, especially Ayatul-Kursi. Increase in supplication (du'a) and seeking forgiveness (istighfar), for whoever is constant in seeking forgiveness, Allah will grant him relief and provision, and supplication is answered as long as it is not for sin or severing ties of kinship. Be strong in resolve and will, relying on Allah, and believing in divine decree and destiny.