I am in my mid 40s and just applied to clinical psych programs for entry this Fall. The biggest challenge for me is jumping through all the hoops that the programs require. When you're an adult and when you have an informed opinion, you can challenge the status quo thinking (which is a plus and a credit to what you can contribute), but it's also a real challenge to institutions and their processes. You may find yourself butting heads with systems you cannot change and following rules that you don't agree with. There's a lot of learning to be had, but there's also a lot of useless, outdated, past-its-prime coursework that the system feels the need to cram into your skull to justify the length of its program and the tenure of its tired professors.