For those of you who live in the local Porirua area, there are several Gym's available that you can join if you wish to.
I have personally used City Fitness Porirua and Jett's Porirua in the past.
Whilst City Fitness has a large facility, you may prefer the cozy option provided by Jett's.
Check the membership options and get underway.
To help you acheive your specific goals, one of my suggestions would be to connect with like minded people. This will help with ideas, motivation, and you may make friends along the way.