Having worked in several companies in more than 25 years, I always feel excited and nervous on my first day. I feel excitement to be working on a new job, a new environment and new team. I feel nervous as I don't know the kind of people I will be working with. There may be some who will be accepting me as part of the team but I always encounter someone who will give me a hard time to integrate with the team. These people consider a new comer as a threat to them. Most of these nasty people are long been on the company and feel insecure when there is a new guy in the team.
Being a veteran job hopper, I tend to overcome these obstacles but in truth, it also gave me some sleepless nights trying to figure out the best way to have myself accepted. A method which almost always successful is to prove to them that you are capable of doing your job efficiently or even better than them.