If you are a parent, it might suit to join a green schools committee or get your school involved.
Extinction Rebellion has a couple of branches if activism and demonstration is what you would like to do.
If you are in a sports club you could maybe encourage zero waste policies and reducing plastic or suggest setting up a sub-group to look at all those issues.
Some other organisations in Kildare:
Birdwatch Ireland Kildare Branch
Sustainable Energy Communities in Monasterevin/Clane/Naas/Johnstown/Maynooth
Zero Waste Community Garden Rathcoffey
Ballinafagh Lake Conservation Group
Volunteering is a brilliant way of helping others and research has shown that it increases our own personal sense of wellbeing too. This of course depends on how much time you have and if you have small kids, it can be difficult to make committments to outside stuff but there are possibilities. I volunteered one morning a week in our local Camphill community garden for a few years and it suited whilst my daughters were in school.
Some volunteering opportunities are listed on the Volunteer Kildare Site and the Irish Peatland Conservation Council also have volunteer opportunities.
Another way to contribute is simply to support eco-business and business in general in your own area. I believe that Community Resilience is going to be more of a focus of interest in the future. With the potential consequences of the climate crisis, we may find that we need to rely on each other more and more and having strong support networks and local food and facilities is integral to this.
Hopefully these ideas have been helpful - as I said, it is not a comprehensive list but more a starting point so do feel free to comment if you have an organisation you would like me to share!
You might also enjoy:
Veganuary - Tips from a Novice
2019 in Review- Reconnection and Healing the Planet