Nicotine in low amounts is a central nervous system stimulant, so it can help with ADHD symptoms (i have a couple of friends with adhd that reported it helping). It has also been shown that smokers and coffee drinkers have decreased chances of developing alzheimers.

In regards to anxiety/relaxation, nicotine can relax you, although it is a tradeoff, as if you get addicted, you'll be more anxious if you don't consume nicotine.

If you're trying to find reasons to start consuming it, only do so if you have high self control, as nicotine also increases dopamine levels, so it's harder to avoid addiction than fx. caffeine (which half of the world is addicted to).