It is completely up to you. However, it’s always important to consider how much you can afford and borrow an amount you feel comfortable with. In fact, if you fail to stick to your mortgage repayments, you may incur fines. In a worst-case scenario, you may even risk having your home repossessed.
Also, there are other important factors you may want to take into account. Your personal situation could change in the future, as you may start a family, take a career break, or find a new job in a completely different field. All these aspects could have an impact in the long run on whether you will be able to cover heftier mortgage debt.