Hi all, I recently got a promotion and a raise (yay!), but my colleagues undermine me because this was taken away from two of the other team members... How do I balance work and my happiness?

Congratulations on your promotion! We cannot control how other feels so just do what is within your control. Continue to perform in your role well and show that you are capable and deserved that promotion. Overtime, your colleagues will come to a realisation. However, if you feel that it is important to, you can consider having a personal 1-1 talk with each of these colleagues separately to share your thoughts and observation in a non-judgmental fashion. Seek their views on how you can support and collaborate with them better to achieve the overall department and company objectives. This way you are indirectly telling them that you want to establish a good working relationship and are being professional about the situation.