The best time in your cycle to... 

If you are someone who menstruates, your menstrual cycle is more than just your period. In fact, it encapsulates a massive hormonal operation going on between your brain, your ovaries and your uterus. As well as resulting in regular, semi-regular or infrequent periods of bleeding, the hormonal fluctuations in your menstrual cycle come into play in a wide variety of ways and, the more you understand these changes, the more you can harness their effects to your best advantage. 
Let's get the basics down, first: for the majority of people who menstruate on a regular basis, your cycle will start with the first day of your period and end when the next period begins, and last between 24 and 38 days. The first part of the cycle involves preparing an egg to be released from the ovary, and the build-up of the uterine lining, while the second half prepares the uterus to accept a fertilized egg and, when that doesn't happen, for the start of the next cycle, controlled by hormonal signals sent all the way from the brain to the uterus. There's a lot going on! 

...go on a date

According to a study from the University of Newcastle, people who menstruate are at their most attractive during their fertile period, between 8 and 14 days after their last period. During this phase, an egg is released from the ovary into the fallopian tube, and our estrogen levels are high; they have to reach a certain level to cause a dramatic enough increase in luteinizing hormone (LH) which, in turn, causes ovulation. Like a hormonal domino effect. 
Both women and men were asked to rate people who menstruate at various times throughout their cycle, and the majority (up to 59%) selected the fertile phase as the most attractive. Interestingly, according to the study, women were more in tune with the changes in attractiveness as pertaining to the moment of ovulation. Hormonal increases will also often result in a higher libido, so all in all it's a good time to get out on the hunt for love.

...lift weights

Your menstrual cycle can also have an effect on your body temperature. During the luteal phase – that's the second phase of your cycle, while your body is preparing for potential pregnancy, your progesterone levels will increase, resulting in a barely noticeable temperature increase. Where you may notice this, however, is in the gym, where this slightly higher set temperature will decrease stamina and endurance. 
Conversely, studies have shown that strength training gains – and new PRs (personal records) – are often at their maximum during the follicular phase. That is to say: having your period is not a good reason to skip leg day! In fact, you could very well get your best squat or deadlift during the initial days of your cycle. (All the more reason to make sure your menstrual cup is keeping you safe, dry and giving you the freedom to focus on your reps.)

...go for a long run

Because your body temperature is higher during your luteal phase, you may find endurance training – like those longer runs, or a super-long spin class – gets a little tougher throughout this time. But the menstrual phase isn't all that much better; you'll find it tough to get your heart rate up during your workout while your uterus is busy getting rid of that lining. 
The absolute best time to get into your endurance run? That would be right after your period ends and before your fertile phase – which gives you a pretty narrow window! What's important to know is that, throughout your menstrual cycle, your body is changing a lot, and there is no such thing as a "bad" workout. Listen to your body, pay attention to cues like more sweating than usual, struggling to catch your breath or simply running out of steam early on, and give yourself a break. Once you're out there giving it a try, you're doing more than most.

...ask for a raise 

Your menstrual cycle has a lot to do with how you feel from day to day – but in more positive ways than you'd think. Despite popular culture telling us that our menstrual cycle is making us irrational, causing us to cry at TV ads for kids' yogurts (guilty) or giving us less patience with our kids, in fact there are a lot of positive ways the menstrual cycle can affect your brain, too. 
While many people report feeling more anxious and irritable than usual right around the time of their periods, and sometimes for a few days beforehand, a study by the BBC shows that the time between ovulation and menstruation – yes, our old friend, the luteal phase – is when people who menstruate will likely be feeling at their calmest, and even that, roughly three weeks after your period, you'll be a better communicator than ever. That makes the luteal phase the perfect time to convince your boss to consider that wage increase you know you deserve. 

...have a heated argument

If it's beginning to seem like the luteal phase might be the best time of the month to do just about anything – except lift weights – you could be on to something! Surely feeling at your calmest is a great time to have that emotional argument you and your best friend have been dancing around for weeks. 
As a matter of fact, not only will you be feeling calmer and like a better communicator, roughly three weeks after your period, according to BBC Future, but you'll also be more attuned to others' feelings – and we all know that empathy is an essential ingredient for the successful resolution of any argument.

...go shopping

If you're someone who loves shopping and has zero issue trying on clothes in changing rooms with unflattering lighting, congratulations! Go shopping any time you like. If you're someone who finds changing rooms... somewhat challenging, to say the least, you might want to pay a little attention to how your body's feeling and what it's doing before you stand in line with your 14 items.
It's fair to say that pre-period, right at the end of that luteal phase, in the last few days of your cycle, won't be an ideal trying-on time for most people who menstruate. Why's that? In preparation for pregnancy, or for menstruation, you may be feeling common PMS symptoms such as bloating and heavy, painful boobs – boobs that do not want to be shoved into a strapless linen vest right now (or possibly ever). 
Do yourself a favor: give yourself a break in the few days before your period, and until it's tapered off to a comfortable, barely-noticeable-in-cramping terms level before you go out to do a wardrobe makeover. Or else be smart: shop online and try on in the comfort of your own home. Just make sure you remember to do your returns within the accepted timeframe!