Hesitant about sharing responsibilites

Consider why you prefer to get work done separately. Usual justifications could be:

• "I'm confident that I can do the work better than others."
• I'll end up picking up the slack and doing it all myself anyway."

Self-confidence and ambition, while good traits, shouldn't come at the expense of a team. A great team needs different characteristics, and it takes a talented leader to create such teams. Ultimately you should trust your colleagues, share responsibilities, and discover creative solutions together.