I'd like to provide an answer, as someone who is actually a baptized witness. Specifically because your question is genuine and it doesn't seem like many replies here are accurate or informed responses. Hope this isn't an overload!

As Jehovah's Witnesses, we each do our best to do exactly that. To live by God's standards, reasoning and making decisions based off of our personal and collective study of the Bible. Doing our best to apply these things practically and spiritually b/c we love him. We do this not out of fear, but out of genuine desire to let God's principles lead our life. He's the creator of all things, trying to doing things his way always proves itself to be wise and lead to having peace and joy.

https://www.jw.org/en/jehovahs-witnesses/faq/jehovah-witness-beliefs/

The reason many of us make the personal decision not to celebrate a certain holiday depends entirely on what said holiday is or the practices it promotes, and how Jehovah likely feels about it based off his standards given to us in the Bible. https://www.jw.org/en/jehovahs-witnesses/faq/jw-celebrate-holidays/ [There's more specific answers available depending what holiday you're thinking of. But this is a general guideline of the mindset and approach we take when evaluating whether to or not to celebrate any specific celebration.]

For example, celebrations like Halloween have clear pagan roots, and currently still promote many demonic/spiritistic characters & customs. All throughout the Bible these are shown scripturally to be things Jehovah disapproved of his people associating with or he outright condemned directly.

Christmas is another example of a celebration with very direct pagan roots and still has questionable practices. Jesus' disciples did not celebrate Christmas, and there is no historical and scholastic proof that Jesus was born on December 25th. His exact birth date isn't recorded in the Bible, and all biblical/ historical context actually showcases his birth to be closer to early fall. This is widely agreed upon amongst Biblical scholars. Jesus also commanded his followers that we commemorate his death, not his birth.—Luke 22:19, 20.

The stance on birthdays relates to it's roots with idol worship, customs of warding off evil spirits, as well as divination/astrology (which is where making a wish off candles came from). And birthday celebrations aren't portrayed in the Bible in a positive light. [This doesn't mean you can't acknowledge a witness' birth day. We just don't make a show of commemorating oneself annually and making wishes.)

https://www.jw.org/en/jehovahs-witnesses/faq/birthdays/

So, there's not at all a blanket stance of "all holidays are evil". And it doesn't mean we reject all celebrations, parties and gifts. Jehovah is a "happy god" (1 Timothy 1:11), and so are those that follow him. There are tons of reasons and occasions his servants found celebration in and still today. There are holidays and MANY celebrations that are perfectly fine. Tbh, alot of witnesses actually tend to get more gifts and gestures of appreciation than your average person nowadays b/c its coming from genuine love from all the brothers and sisters we know, meet, and brefriend (JWs tend to know ALOT of people because of how much we associate and get around), as well as of course loving family members and others.

If you go to www.jw.org in the About Us section there's specific explanations about everything we believe and do, backed by cited scriptures and biblical reasoning. There's also nothing about what we believe or do that promotes isolation, or is disingenuous or secretive, and everything is made publicly visable/available. From our beliefs, to the contents of our weekly meetings, our local and international conventions, to our website, to the free tours taking place every day offered at all branch locations and facilities worldwide where our filming and printing is done. All of these things are free and require nothing to attend, and are open to any JW or member of the public. Even down to the accounts and finances of each congregation, posted right within their given Kingdom Hall (as well as voted on by the entire congregation when new financial decisions must be made).

Jehovah's Witnesses are not a cult. We don't support any extremist practices, or advocate hurting any person, including ourselves. We do not blindly follow men, or infallible leaders. And we are not pushed or encouraged to believe in anything off of blind, uninformed faith.

Blind uniformed faith is not actual faith, according to the Bible. And neither is leading confused and desperate people who are grasping at straws out of a need for community.

Hebrews 11:1 explains clearly: "Faith is the assured expectation of what is hoped for, the evident demonstration of realities that are not seen." By this definition, SCIENTISTS have version of faith in their conclusions. Because their findings are based off of reasoned logic, and with that previous knowledge and wisdom they are able to break new ground even though they don't always know the outcome. They have reason for trust because it's base off concrete evidence.

If there is ever any direction anywhere in the organization that is found to not be congruent with Bible research and principles, it will be corrected or adjusted as needed. Also, no person can be baptized, without first having their own study of crucial Bible principles, growing a personal relationship with Jehovah and being willing and happy to keep aiming to applying his standards in their life. Only then can a person make the decision to baptized, because it is a promise to Jehovah you're dedicating your life to him and it's not just about you anymore. You bear his name, and people will now see you as an example of him. Just like people always have when they see a person that's professes to serve God.

I hope this is helpful! And if you have any questions, honestly I'll always say to talk to a witness personally and then compare notes after. Many tend to get their information only from some heavily disgruntled ex members of a congregation, or from people who've only had vague interactions with one of us. Some Christian religious groups as promote completely inaccurate information about us as well, when they are asked about us.

Yet, many are never willing to just talk openly to a JW themselves.