I'm a 76-year-old woman and haven't been sexually active in many years. Is it too late to resume sexual activity?

You can resume sexual activity at any time, as long as you're willing to invest a little time and patience. 
With age, the vagina and vaginal opening often become smaller and the vaginal lining becomes thinner — especially when estrogen levels are low. As a result, it can take longer for the vagina to swell and lubricate during sexual arousal. Together these changes can make sex painful. 
To make sex more comfortable: 

• Begin with foreplay. Foreplay helps stimulate natural lubrication.
• Ensure proper lubrication. Try an over-the-counter lubricant, such as Astroglide or K-Y lubricating jelly. If sex remains painful, ask your doctor about vaginal estrogen therapy — available as a vaginal cream, tablet or ring — or other treatment options.
• Try various positions. After a long period of abstinence, it may take time to stretch the vagina so that it can accommodate a penis. Experiment with new positions to find what feels best.
• Ask your doctor about a vaginal dilator. A dilator is a smooth plastic tube you can use to gently stretch your vaginal tissues. Your doctor can help you choose the correct size. He or she may recommend placing the dilator in your vagina for several minutes at a time, several times a week. You may also choose to use a vibrator several times a week for the same effect.

In addition, keep in mind the need to practice safe sex — especially with a new partner. There's no age limit for sexually transmitted infections. Use a condom every time you have sex, and discuss testing for sexually transmitted infections with your partner. 
Finally, remember that there's more to sex than intercourse. Activities such as talking, touching and kissing can help promote intimacy and lead to sexual satisfaction.